That’s exactly the problem. Wayland is a set of standards, more akin to FreeDesktop.Org than to X. It lives and dies by its implementations, and it’s so utterly dependent on them that “KDE Wayland” has started to become its own thing. KDE are pretty much forging ahead alone nowadays and when they make changes it becomes the way to do it. Also what they do can’t be shared with other desktops because they’d have to use KDE’s own subsystems and become dependent on its whims.
It wasn’t supposed to be “Kdeland” and “Gnomeland” but that’s what it’s slowly becoming. We’re looking at major fragmentation of the Linux desktop because desktop teams have and do stop seeing eye to eye on major issues all the time. And because there’s no central implementation to keep them working together they’re free to do their own thing.
