> Every single thing you've mentioned can be fixed with Xorg/X11.

Then why hasn't it been fixed?

In open source, those who make the code get to make the decisions--for better or for worse.

My personal opinion as to why X11 gets so few contributors--the build system is so terrible that nobody wants to touch it anymore. I suspect they would get a lot more contributors if they changed to something like meson/ninja which doesn't need to recompile the universe to be correct.