If by better you mean legacy code which is hard to refactor and cannot be adapted to a modern environment without breaking everything. Might as well start fresh, that’s what mac os did and for good reason. Go ask a pen tester whats easier to break into. In the modern day of surveillance, security for the common user becomes important. If it was that easy it would have been done a long time ago. Apple has a vested interest in it, Red Hat does, Suse does, Canonical does. Why hasn’t it been done? Just like systemd there was a need for it. Is it perfect? no. Does it have to be? no. x11 was written with main frames in mind. Does any one own a mainframe anymore? didn’t think so. It’s a different time, different solution.