In an ideal world that would be great practice. But when Meta is sitting on 95% of the activity pubs usage, it’s just not going to be feasible to tell them “your problem”. Because that’s what users are going to be pushing for. Perhaps not you and me, and perhaps not many of those that have used services if the protocol for a while.
But the millions and millions who will be coming? They don’t care about Meta taking over. They’ll be mad when Mastodon stops syncing, or pixelfed. Who at that point have grown so much that there’ll be a huge public outcry if they don’t bend over backwards.