Indeed, but GNOME is big enough to veto against anything they dislike getting into Wayland. And indeed, TWMs were brought up as a big reason why CSD sucks; window decorations primarily contain controls for the window manager and the form these controls should take depends entirely on the nature of the window manager, therefore the window manager should draw the controls. But GNOME doesn’t want to perform the oh so difficult task of providing window controls to apps that don’t provide their own under Wayland, so too bad.