You do realize that the whole of meaningful architecture we have builds on, and often gives way for legacy ones? XWayland is made by Wayland, because obviously not every software will port overnight or ever. That’s a positive thing.
It’s almost like the linux community is not controlled by a dictator like Apple, where they can just say “we are using this API from next version, if you wanna work, port”. Wayland required a critical mass before it actually started flying - but it definitely flies now.