Nobody is developing x.org because it's a hot mess. It's just been half-baked solutions smacked on top of each other. That's why hardware acceleration barely works and artifacts are just a fact of life.

It's just that Wayland is newer, it's that x.org is a dead end and has been for many decades. If other people want to develop it, then by all means. But they're not, and ultimately I can't put a gun to someone's head and force them to work on a codebase. So here we are.