Also, it was easier to support X11, since there is no security. You wanted to read other applications key events, no problem. Want to read the screen, without without anyone knowing? No, problem, just read it.
With Wayland you must use APIs for stuff, and you are not allowed to do everything.
X11 is an ancient piece of crap which no one wants to update or maintain.
Wayland is the new and better display manager.
However, many old applications only support X11, because they depend on some arcane feature not yet supported by Wayland. Hence, the drama.
Also, it was easier to support X11, since there is no security. You wanted to read other applications key events, no problem. Want to read the screen, without without anyone knowing? No, problem, just read it. With Wayland you must use APIs for stuff, and you are not allowed to do everything.