Well, it's funny how something with "the underpinnings of how X11 does it are actually decrepit and inefficient and compare poorly to other strategies that leverage different entry points that Wayland actually preserves" still manages to solve the problem, and Wayland doesn't.
X11 isn't perfect. Nobody's ever argued that. It's just nobody's really asking for a replacement, and if they were, they wouldn't be asking for Wayland. X11 is an extraordinary piece of technology, it takes some gal to claim everyone should just throw it out and replace it with a ground up rewrite that adds no new features and doesn't support the major features X11 is famous and loved for.
It's not like init/SystemD, where init really was a bug ridden piece of garbage that's needed replacing now since before Linux itself came on the scene, and SystemD implements everything init did but does it right.