The discussion I stumbled upon, about this SSH app for Android, is really worrying. Will Google really manage to make it impossible to root your phone?
But there's more to this, it's more complicated. In the Big Picture, Google has every incentive to make these changes — they lead to more security, and they're aligned with Google's corporate goals as well.
When talking to users, Google will emphasize control over hackers.
When talking to stockholders, Google will emphasize control over users.
Edit: I disagree with "they lead to more security". That's not "security", let's not turn words upside-down.
There are phones with locked bootloaders. But for now there are ways to unlock them. In theory though they could just lock the bootloader and that's it, if you can't jailbreak the device or root the stock ROM you're out of luck.
Yeah, my experience was mostly from that time. For example with an original Galaxy S (custom ROM + overclocking).
I also had a OnePlus One, which was unlocked of course, but the key combination to get to the bootloader was super unreliable or straight up didn't work at times.
Funny thing is: Now that it's easier to install a custom ROM I've just been running stock for years.