That's complete horseshit. There are lile 3 major implementations of Wayland and 2 exist because the other one wasn't ready at the time. There are other hobby implementations, but they all work together. Just like how different network stacks can all talk TCP to each other and be fine. Nobody calls TCP fragmented because there are different network stacks...

There are also smaller projects.

Also, the model of a protocol allows Wayland to be deployed on truly exotic operating systems. As long as the top level is compliant, shit just works.