The ability to stop applications from keylogging you, secure and efficient screenshare, decent compositing, not to mention all of the cruft it’s obtained over the years that stops it from obtaining all of these. And, as a whole, Xorg is completely incompatible with multi-monitor setups - no fractional scaling, and no multi-monitor scales, as well as refresh rates as you mentioned.
All we should be using nowadays at most is Xwayland. You only get a pass for bare X if: