Yes exactly, it's always a big debate every time a new features is needed whereas it should be Wayland protocol or Dbus.

Gnome people push for everything Dbus, and many Wayland dev prefer to standardize over Wayland protocol.

It's kinda sad that the APIs are fragmented over two IPC solutions (unlike for eg on Android where everything goes through Binder IPC).

I think the overall the idea is : if it requires permission/sandbox -> Dbus, otherwise Wayland . But in practice there is a lot of disagreements.