You are absolutely correct. This is why it is absolutely reasonable to assume that Wayland is actually a sabotage project.
X11 was far ahead of anything out there when we had compiz with spinning desktop cubes and wobbly windows running absolutely smooth even with the most basic GPU in 2006(!). Something had to be done about that.
Sabotage project? X was "smooth" in 2006, it hasn't moved along. Mixed framerates and resolutions are horrid to use. Performance issues appear with just one 4K screen. High-framerate, FreeSync or high bit depth displays are basically a waste with X.
The only thing X (and KDE) seems to have gotten right is mixed (and fractional) scaling, Windows can't do even decimal scaling properly within just the core UI.
X11 was far ahead of anything out there when we had compiz with spinning desktop cubes and wobbly windows running absolutely smooth even with the most basic GPU in 2006(!). Something had to be done about that.