I don't know about mess. Is it an emulator collection? Dolphin is a Gamecube emulator. Would that be a good addition to mess?
Maybe one good reason is to constrain project goals in scope.
Maybe one good reason is to constrain project goals in scope.
So a significant portion of what makes Dolphin so good would be rejected from MESS on principle. That isn't an inherently bad thing because MESS/MAME isn't really intending to be efficient & "fun" but rather is an archival project designed to allow perfect reproduction of the works indefinitely into the future.
Then I can easily see why Dolphin would have no interest in joining such a project; what with the incredible focus on and borderline unbelievable achievements with performance they’ve made.
Totally different projects, totally different goals.