And it will become more as development focuses on Wayland. If you look at X11's release history, there is (and has been for quite some time) only the most important things going on. That doesn't necessarily mean things are impossible to do with X11. But it's just the way things are once something slowly gets replaced by something else.
Also, doesn't Wayland do things x11 can't, or did badly, like Variable refresh rate ?
Fractional scaling (per-display), input isolation...
And it will become more as development focuses on Wayland. If you look at X11's release history, there is (and has been for quite some time) only the most important things going on. That doesn't necessarily mean things are impossible to do with X11. But it's just the way things are once something slowly gets replaced by something else.