No idea. I tried it a couple months ago on Debian (I think I even posted the screenshot here in the show off thread). . . And just a couple days ago on EOS.
In both scenarios I was ALSO prompted with at login for GNOME and both times I was able to log into a fully functioning GNOME experience.
I don’t discredit your argument, but in real world application, that did not happen for me. And since I based my view as to what I experienced and not the theoretical experience you’re offering. . . Well, you get it.
So, when I install budgie, I also got a complete GNOME environment as well.