Google is quietly blocking RCS on rooted devices.

Less bloat ware/spy ware - custom ROMs don't come prepackaged with random shady games from shady companies or random shady social media apps from shady social media companies.
Better privacy and security implementations along with DeGoogling - a lot of ROMs offer Gappless ROMs which is really important since Google is way to big and has too much influence on android OEMs and its easily the biggest ad company in the world and constantly refused to respect peoples privacy. e.g GrapheneOS https://grapheneos.org/features and DivestOS https://divestos.org/
Long term software support to help against e-waste e.g LineageOS supports so many phones who's manufacturers have stopped supplying software updates. https://wiki.lineageos.org/devices/
Customization e.g Crdroid includes loads of custom settings from a variety of other custom ROMs and OEM ROMs that rarely get implemented by any stock ROMs. https://crdroid.net/
Rooting android phones gives users the ability to access system files that they may not have been able to backup if the apps don't support it. It also allows for a full system backup and restore
It also allows users to block ads and unwated connections without using a local VPN e.g adaway

Enabling Google to dictate what a user can do with their own device by limiting features is a slippery slope and the last thing we want to happen is for Android to end up like iOS with its walled garden approach.

The walled garden is something that grows fast everywhere. Users should have the rights over their devices. Maybe its time to get the EU on this train, their last approaches like the GDPR or the DSA are from near the same spirit.
- Its unlikely that they'd get involved, RCS might be default on Googles messenger app but people still mainly use alternatives like WhatsApp so there's not a big enough user base that would be affected and since Google is pushing RCS as interoperal, DSA won't apply.
- Yes, OS supported root should be mandatory, it shouldn't have to be some sort of hack.
You can still install custom roms without root enabled. Enabling root access is an optional step on most custom roms installation as long as your bootlooader has been unlocked. The question is, does google disable rcs on such devices too, or is it just on rooted devices?
- As of 2024, Google is now quietly blocking RCS messages on unlocked/rooted android devices. Even if your device only has an unlocked bootloader, it is now at risk of being quietly shadowbanned from sending RCS text messages.
  
  According to the OP that opened the issue with Google, it doesn't work with devices with unlocked bootloaders so it would affect the majority of custom ROM users since very few custom ROMs and devices support relocking the bootloader, and I think it probably would still affect these devices too since the last time I relocked a bootloader with DivestOS I still had the error message about system integrity on boot
  
  Rooted users can probably bypass this issue with some Magisk modules the same way they do with GPay and banking apps.
  
  If Google really does want to push RCS then disabling access to the more technically inclined users now seems a bit silly.
  
  I thought they'd at least wait for wider adoption before locking it down like they're doing with YouTube and ad blockers, especially with imessage and WhatsApp being such big competitors. At least in Europe, I don't see anyone dropping WhatsApp for RCS anytime soon.
  
  Rooted users can probably bypass this issue with some Magisk modules the same way they do with GPay and banking apps.
  
  That doesn't work anymore due to hardware attestation
  
  Works fine for me, banking and gpay
  
  Yeah this will cause issues because many device that allows relocking bootloader can only do it once, which lock out future rom upgrades.
  
  What prompt google to do this? Do they have bots problem abusing the service?
  
  I've been degoogled since 2019 so I have never actually used RCS so I'm not 100% sure.
  
  If I were to guess I would assume it has something to do with Apples support for RCS. The last time I checked, Apple won't support end-to-end encryption in RCS and the messages are only encrypted in transit so maybe Android users that will use RCS with Apple users will have all of the chats saved unencrypted within the system folders and that would be no bueno for Google
  
  But I'm honestly not sure, I have no interest in learning about RCS unless GSMA helps open source apps integrate it so I'm not stuck with either Samsungs or Googles messaging apps
  
  I have no interest in learning about RCS
  
  I never will. It's too little, too late.
  
  20 years ago it would've been a god replacement for SMS. Today? I only use SMS with people who refuse to switch to any modern messenger. I was using XMPP on my phone 20 years ago...
  
  You can only relock once? Since when?
  
  Or do you mean relock once with current OS? Yea, unlocking requires a reset, as a security mechanism.
  
  iirc many chinese phones can only be unlocked using the stock rom, so if you lock it while using a custom rom, you better not planning to unlock it again.
  
  For practical purposes its capturing revenue from OEMs and users. Android being open source if they didn't completely sabotage an actual open source market they could well find OEMs or third parties capturing those dollars or indeed those unearned dollars evaporating in a competitive market. Think the IBM PC and Microsoft.

You want an example? GrapheneOS, to take back my privacy.

Speak for yourself.

I was speaking for myself, I have no idea why people do it. Didn't say there aren't legitimate reasons, I just don't know any of them
- I have installed custom ROM (PixelExperience) on my Moto G5s Plus. This way I extended its life by 2 years. The stock ROM only went up to Android 8.1 and was very slow and buggy, unlike with Android 7. This way I got Android 11 which was newest at the time. It was also much faster than the flawed 8.1 update.
  Additionally, PixelExperience allowed some nice things. It looks like Google Pixel phone, even to Google, so I got free unlimited photo/video backups. This may be against ToS, but it's not like I said I have a Pixel 5, they decided that I do ¯⁠\_⁠(⁠ツ⁠)_⁠/⁠¯.
  Another really great thing is routing Wi-Fi hotspot over VPN. I definitely don't want someone using my internet connection raw.
  
  Next, root. I have only done that with Samsung Galaxy Ace from 2011. No locked bootloader BS, just flash, Tada! Rooted.
  This allowed me to do full backups, including apps on that device.
  
  But there's countless other uses, most of which I forgot. Some that I can think of that would be useful to me are:
  
  Proper firewall
  
  Access to Android folder (without using desktop) (removed since Android 11)
  
  Full app backups
  
  Routing hotspot over VPN
  
  Band locking on Qualcomm SoC (possible without root on Exynos and MediaTek)
  
  WPS push and WPS pin Wi-Fi connection (insecure) (removed since Android 9)
  
  Opening ports <1024
  
  Changing screen resolution and aspect ratio (useful for screen mirroring)
  
  Removing bloatware
  
  Changing Wi-Fi MAC address manually
  
  Battery charge limiting (e.g. to 80%)
  
  Precise management of app permissions
  
  Proper firewall
  
  What services does it have that are listening on external interfaces?
  
  It's not necessarily about listening.
  
  Many/most apps try to connect to Facebook, for example. Part of the ghost profile issue.
  
  Or a handful of other data gathering services.
  
  Blocking those are useful for both privacy reasons and battery life.
  
  Those apps like to run in the background at al times, registering for every single receiver the phone has (apps like Solitaire, for example). If I didn't block receivers many apps would run all the time, even apps I use once a month.
  
  It's MY phone... End
  
  That's the point. I don't know.
- Privacy? I am astonished that you're seriously asking this.
  
  Is this the point about unlocking the bootloader being risky, or did you just pour the Google/Samsung advertisement ethos down your throat?
  
  I guess that's a fair reason. I hadn't really considered that because I don't personally care too much
  
  I'm interested; are you saying you don't care about privacy from your android device?
  
  I don't care to enhance it any further from the default experience, especially with the downsides
  
  Downsides?
  
  Can be quite a bit buggier than stock, can be difficult or impossible to use some apps. You can lose some stock features sometimes. You can spend a lot of time debugging issues.
- You're talking about other people, not yourself.
  
  The internet is chock full of people rooting. If you don't know why other people rot it's from willful ignorance.
Meh, they were speaking to the other population. They speak for most.

Because it's my device, not Googles.

Do you let Dell lock down your laptop and prevent you creating an Admin account?

What I do on my PC and what I do on my phone are different. Above all the most important feature of my phone is that it works reliably, not that I can tinker or install mods
- tinker or install mods
  
  lol, tinker and modding is one of the two things I do most on my phone.
  
  Telegram community is way more active than XDA for my phone.
  
  Different uses for a phone then I guess. To me my phone is an appliance like my washing machine. I want it to work when I need it to and be reliable.

for me , privacy. no google services run in my phone, and none od my data gets shared with anyone

Because it's my fucking phone.

Custom "rom"s extend the life of the device via both security updates and app compatibility. They're usually able to be used without propriety Google shit at all, if the person wants.

Just rooting allows more control over what is and isn't on the device, which goes back to the "my fucking phone" factor as well as the rest.

Yeah, you can partially debloat via adb, but that's a partial solution to a systematic problem.

And that's ignoring apps that can do more with root, if you want them to have those abilities.

Edit: hell, just access to hosts file is enough justification.

Custom roms: I don't want google service on my device.

As to rooting, I have rooted in the passed, its my device and I'm a tinkerer so why not?

Might as well ask why people run linux after buying a laptop with pre installed windows.

Well Linux is an entire different OS which comes with its own benefits. Rooting makes it a lot more difficult to use apps that use safetynet so doing it because "why not" rather than for a specific benefit doesn't make sense to me
- I need root for some things like IsoDrive and Frida. Frida would be usable without root but it's really cumbersome. Also AdBlocking and some LsPosed modules like CorePatch. WireGuard works better with root aswell because you can use the kernel module directly
  
  I also hate being restricted by arbitrary locks, it's my device so I wanna be able to do whatever I want with it
- Android is Linux with a patched kernel and a different userland. Are you saying you never use root on Linux?
  
  My usage of my phone is different from the usage of devices I specifically install Linux on.
  
  Being root gives you access to the firewall and better access to controls over apps. Although maybe you don't care
  
  That's fair, but yeah I don't really care for that. I can understand why someone would though
- OK, if you want a whole different experience there's some mobile GNU+Linux distros like Ubuntu touch, Postmarket OS or Mobian.
  
  I don't want a different experience, I know you can install different Linux OSes on your phone but that's not what I use my phone for. Last I checked Ubuntu touch barely worked too.

How do you keep a phone more than 5 years while still having security updates without a custom ROM?

I had my note 8 for longer than security updates existed so I installed lineageOS on it, it got security updates but lost a ton of other features and became buggy and slow. Maybe with other phones the experience is better.
- I'm running a 2018 flagship using DivestOS (a fork of Lineage). It's faster than most new phones, battery gets charged midday (because I hammer it), and I'd argue more secure than most (because I have a proper firewall and some other security tools.
  
  If I were to not hammer on it, the battery would last for 10 hours+ (using just messaging apps, instead of ftp, file sync, games, etc).

Delete bloatware or just straight up remove all of the Google services

Personal firewall.
If an app doesn't need internet access to do its job, it doesn't get it. Simple as that.

I'm running a laptop replacement chroot

You need to differentiate between root and custom ROMs. Root is counterproductive in regards to security, because it significantly increases attack surface, but Custom ROMs like GrapheneOS can make your device much more private and secure. It also doesn't ship any proprietary apps by default and Google Play services are sandboxed and isolated, just like any other app. It's pretty amazing.

It's not necessarily counterproductive, it depends on what you're trying to accomplish
- *counterproductive in regards to security, I updated my original comment
  
  Even then it's not.
  
  Is your PC less secure because it has root access/Admin accounts?
  
  It's all about how it's managed. And I'd argue my phone is more secure, because of how I use root to improve security.
  
  Good luck installing any app on my phone, without knowing how to unlock that functionality.
  
  I recommend the following section of this article:
  
  Rooting your device allows an attacker to easily gain extremely high privileges. Android's architecture is built upon the principle of least privilege. By default, only around 6 processes run as the root user on a typical Android device, and even those are still heavily constrained via the full system SELinux policy. Completely unrestricted root is found nowhere in the operating system; even the init system does not have unrestricted root access. Exposing privileges far greater than any other part of the OS to the application layer is not a good idea.
  
  It does not matter if you have to whitelist apps that have root — an attacker can fake user input by, for example, clickjacking, or they can exploit vulnerabilities in apps that you have granted root to. Rooting turns huge portions of the operating system into root attack surface; vulnerabilities in the UI layer — such as in the display server, among other things — can now be abused to gain complete root access. In addition, root fundamentally breaks verified boot and other security features by placing excessive trust in persistent state. By rooting your device, you are breaking Android's security model and adding further layers of trust where it is inappropriate.
  
  A common argument for rooting is that Linux allows root, but this does not account for the fact that the average desktop Linux system does not have a security model like Android does. On the usual Linux system, gaining root is extremely easy, hence Linux hardening procedures often involve restricting access to the root account.