For now. They're still in their growth phase. If they ever become dominant and they need to make money, they'll turn into a walled garden like every other. Everyone seems to forget that Twitter, Reddit and Facebook were also all about openness at the start

Oh, well that's good anyway. Is it true that they only have like one major server? Because I've heard that, but I haven't looked much into them, so I'm not sure if it's still the case or not. To my understanding, they are meant to be a federated network, but really only have the one server.

The bridge is necessary because BlueSky and Mastodon cannot federate, and they never will be able to. ActivityPub and ATProto are different protocols.

Not only federates but can also be partially self-hosted and is also open-source - by the way, I don't mean it's perfect but a lot better to reach people from there than Twitter, but be wary of this), anyone knowledgeable of US politics will know the names mentioned and how shady it looks. I still think Mastodon isn't ready for this kins of exodus. People who waited this long to leave either wants convenience or is waiting for some of the people they follow go elsewhere, or both. Mastodon has too many mobile apps options, BlueSky official app is so much closer to how Twitter looks like and people are used to and don't need to choosee instance as it already comes pre-selected by default (although people can change). Then comes the issue of scability if there was an instance to be the "default" for these people who just want quick and convenient alternative, will it be able to handle this much people at once? I have no idea but I doubt it. Most of us who go find alternative in the Fediverse is aware privacy-focused alternatives usually more than often comes at the price of convenience, not really the mindset those people are in, hopefully some of them get into it by learning what decentralization is from BlueSky?