Wayland does only do the most basic stuff and leaves everything else to the compositor (aka Gnome or KDE). That means every compositor will implement their own hacky version of the missing functionality and it takes ages until that gets unified again, so that apps can actually use that functionality.

Would this functionality be mostly the same? Could they get together to make a shared libcompositor that implements the bulk of the functionality? Or is it so tied to specifics of the desktop environment that there’s little commonality. In which case, Wayland not doing it would be the right call.