The difference is that x11 was SK bag that you required a tons of plugins to have a working system(xorg) and no one could reliable maintain that mess of codes and plugins where every change could break another
The extension situation is already much worse in Wayland than in X11. In my X11 server there are about 25 extensions and only a handful are required for modern desktop functionality. Wayland already has well over a hundred extensions (protocols) and dozens of them have to be implemented by each compositor just to get basic stuff working.
I have a news flash for you, the situation with extensions in Wayland is ten times worse than X11. Wayland requires an extension for what used to be considered basic functionality in a desktop environment.
Could've fooled me! I've only ever seen Linux devices run Xorg. Maybe some embedded hardware runs an alternative, but Xorg seems to be the de facto standard for desktop Linux.
This isn't a big issue because Xorg splits a basic GUI into dozens of different daemons and services (compositors, window managers, input daemons) so it seems like there are different X11 implementations even when there's usually only Xorg.
Give Wayland a bit more time and it will also ossify to the point where it becomes unviable to create competing implementations. Most of the smaller compositors are already there.
