Linux

Then there’s accessibility functions, which wayland breaks almost by design by denying apps access to each other. Even something as simple as an on screen keyboard becomes nearly impossible to implement.

That's a side effect of just dumping everything into X11, once you switch from it you lose all the random kitchen sink warts it grew over the years.

Like an on-screen keyboard shouldn't be fiddling with a display protocol to fake keyboard inputs, it should be using the actual OS input layer to emulate them (So then it'd work with devices that read input directly and not go via X11). Same with accessibility, there's a reason other OSs use separate communication channels with their own protocol.