Comment by kllrnohj
> given that we already had a working GUI. (Maybe that was the intention.)
Neither X11 nor Wayland provide a GUI. Your GUI is provided by GTK or QT or TCL or whatever. X11 had primitive rendering instructions that allowed those GUIs to delegate drawing to a central system service, but very few things do that anymore anyway. Meaning X11 is already just a dumb compositor in practice, except it's badly designed to be a dumb compositor because that wasn't its original purpose. As such, Wayland is really just aligning the protocol to what clients actually want & do.