There's an increasing amount of wayland compositors, so I don't think diversity goes away.
Additionally, hyprland supports plugins which can do most things an X.org window manager could do. E.g. there's a plugin to support river's window layout protocol, which allows for creating custom window layout generator.
Diversity doesn't just vanish, it's replaced by new possibilities, created by solid protocol specifications with multiple implementations.
Similarily, nixpkgs and other repos continue to grow, just like flathub does too. These projects aren't killing diversity, they're enabling it.
I would argue they are all the same since most are based on wlroots and if wlroots doesn't support something neither does the "increasing amount of Wayland compositors".
Systemd makes it easier for distro devs to write new services and test them, and makes it less likely for those services to have bugs. The systemd project also provides many daemons that improve the quality of a distro, such as journald, systemd-boot, systemd-resolved, and systemd-timedate. Systemd is making it easier for small distros, not harder.
I've ran into so many problems with systemd, that I just avoid it now. You do one thing and expect that to reflect on whatever you think it should reflect on, and it doesn't. Why? Some systemd thing does this or that and it doesn't let the message through. Ah, but you have an exception list for that. OK, cool, add to exception list, still doesn't work 😒. Turns out, that exception list thingie is like in beta (for as long as systemd exists), and it doesn't really work... well, at least not most of the time.
Not to mention various errors, daemons not responding (for god knows what reason), things being incredibly slow (compared to non-systemd based distros)... I just gave up, that is not a finished product from my POV.
I use Void now with runit, couldn't be happier ☺️. Everything just works. If it doesn't, it's probably my fault.
Choice is one of the great things about Linux, and I don't see alternative init going away. For most people systemd is good enough and solves problems, so I agree, in that case popular init diversity has gone away.
Linux'es diversity has never been found in the large fundamental pieces of software. Instead it's typically been found in the nooks and crannies between them. We've typically had one or several of those and most have used those. It's the kind of diversity you find between evolutionary differences between the same species, not revolutionary differences.