I think Wayland is a classic example of 'we do these things not because they are easy, but because we thought they were going to be easy'.
X11 was released in 1987, and I remember using an SGI workstation in 1992 running IRIX, and that had a perfectly functioning X11 desktop which wasn't much different from today's desktop environments. If X11 could be done in a bit over 5 years with late 1980's development tools, it's kinda bizarre that Wayland takes so long.
Part of it is because X11 has improved a lot between 1987 and now. It’s not just been static.
So Wayland has to capture those 37 years worth of engineering.
But also, X was designed in a way that facilitates rapid development and easy integration. In exchange, you get some significant issues which are what Wayland is trying to solve.
So Wayland has to engineer something much more difficult at its core.
Lastly, Wayland has to deal with a much more bifurcated system with a lot more legacy applications to support. X11 came up at a time where there were significantly fewer distros, computers were far less accessible and there were in turn, way fewer programs.
In many ways, most of Linux was designed around X. Now Wayland has the job of trying to unroll it all, across many distros and many more users with many more use cases.
IMHO it’s not a good comparison to make.
I do think there are several areas where Wayland has failed in planning and execution (imho by not looking at windows or macOS), but I don’t think its areas that X11 really did much anyway.
X11 was released in 1987, and I remember using an SGI workstation in 1992 running IRIX, and that had a perfectly functioning X11 desktop which wasn't much different from today's desktop environments. If X11 could be done in a bit over 5 years with late 1980's development tools, it's kinda bizarre that Wayland takes so long.