It's not about being on different teams, it's about joining the Avengers. Like if there is a newly created team not named the Avengers then that's fine, but putting prominent characters from other teams on an Avenger team feels like it dilutes both.
Like if they included someone like Gambit was put on an Avengers team then I'd be fine, but putting a member of the O5 in feels wrong. It would be better to create a new team without the Avengers name.