Wayland is fragmenting things, complaining that someone else is doing the same thing that they are (developing a new display interface) is what I find hypocricical.
As I say, technical arguments are fine. But the wail of "but they can't do that, WE are the anointed future" is not.
And it doesn't matter if we are talking Wayland, Gnome3, AOO or any other tool.
Even if it's the same developers, if you choose to create a new project that is supposed to replace the way things are currently done with something new (and the new project doesn't have to be a different name, as Gnome3 has shown us), you have absolutely NO right to complain if someone else also creates a project to compete with you. Even if they start a while after you do.
This goes even more if your replacement isn't intended to offer all the capabilities of what you are replacing (and in terms of Wayland, the fact that you can support X clients by adding another layer to the display stack doesn't count as offering the capabilities of X)
not that you have much right to say anything even if you are a long-established codebase that you aren't replacing. But there you can honestly talk about fragmentation and argue for compatibility.
But really, projects should compete on technical matters, not fussing about "how dare <someone else> choose to do something different". Linus has the right attitude here. He has said that he fully expect that at some point, someone will create a replacement for Linux that is nimbler and cleaner, and at that point Linux will deserve to be replaced.
Supporting Freedom for users requires that you not only make it easy for others to start using your project, it requires that you make it easy for others to migrate away from your project and use competing projects as well (especially if the 'competition' is an earlier version of your own project)