I guess for me the difference is that the kernel is just way beyond what I can understand and has never had any viable alternatives, gnome I really don't like, and everything else you listed is just collections of simple stuff that aren't actually very interdependent. Systemd is a giant mess of weirdly interdependent things that used to be simple things. Sure, some of them weren't great, but every major distro abandoning all of the alternatives feels like putting all of our eggs in one basket that's simultaneously getting more important and more fragile the bigger it gets.