Similar things have happened on the fediverse of course. Personally I am not as opposed to having global search for *public* posts; I think that's semi-inescapable. Whether it should be opt-in or opt-out is a different thing.
But I think what's true both on the fediverse and bluesky is that people are communicating in ways that easily *can be* indexed and which are public and I think people want more community-oriented private communication than feels "easy to do" on these systems.