One important point to note in these discussions is that X.Org is a specific implementation of the X11 protocol (the canonical implementation as it happens).
Wayland is the protocol and compared to X11 in this context. There are multiple implementations including:
1) Weston (the reference implementation)
2) Mutter (Gnome)
3) Kwin (KDE, also implements X11)
It's important to draw the distinction as many/most of the limitations people come across are in the implementation not with the protocol. People using different implementations will come across different issues too.
> People using different implementations will come across different issues too.
...which is the biggest problem of Wayland in my opinion.
By defining protocols only, we now have the development fragmentation problem. The desktop experiences will be more inconsistent between DEs than the era of X11, and minor DE users eventually are forced to switch to major DEs like Gnome because other DEs won't have enough devs to maintain its low-level implementation.
Wlroots as a library for implementing a Wayland compositor has done wonders to help develop small-scale Wayland "desktop environments". Sure, you pull the whole wlroots things, but under X, you pull xlib, plus some X11 server.
Wayland is the protocol and compared to X11 in this context. There are multiple implementations including:
1) Weston (the reference implementation)
2) Mutter (Gnome)
3) Kwin (KDE, also implements X11)
It's important to draw the distinction as many/most of the limitations people come across are in the implementation not with the protocol. People using different implementations will come across different issues too.