The application not being forced to handle the title bar and its buttons, but getting the default one for free. I wonder when the GNOME/mutter people will discover such a novel concept (regarding Wayland).
They are very intentionally choosing to put that responsibility in the client. It is very irritating and their choice (as opposed to other compositors that support the decoration protocols) is one of the bigger sources of Wayland fragmentation.
Um not really.If the application gets stuck, Windows Desktop Window Manager slaps its own titlebar on top of the window, ignoring all client decoration. You can still move it or close it.
On GNOME, if the application gets stuck you have to kill it by other means.