I'm with Derry in that the big A clued me in, but it's also something of a tradition. Continuities where the Avengers exist but don't use one of Tony's properties as a collective home, or at least a team base, are very much in the minority—so much that I can't think of one. Even in Ults they used the mansion, and in a lot of ways they edge closest of all the comics to movie continuity.