Yup. Up until roughly the times of early Twitter, federated, decentralized communication systems were the obvious norm to any engineer designing one.
Twitter was even meant to be federated and decentralized. I had interviewed one of their first engineers (this piece is about BlueSky, and in Polish; the Twitter thing is important background), who was there and working on that in the very early days. They had a proof of concept. But then the VCs got involved and the decision was that it would be harder to make money on a decentralized service. Rest is history.
Yeah. Thankfully, Fediverse is a bunch of independent projects. There are Pleroma, different Misskey forks, Lemmy, kbin, Pixelfed, Loops, GoToSocial, and dozens more.
Mastodon is still probably the biggest, user-count-wise, but if Mastodon does a real stupid, there's going to be a fork that takes over the mindshare and the instances. This happened with OpenOffice → LibreOffice when the former got taken over by Oracle; this happened with XFree86 → X.org. This happened with ownCloud → Nextcloud.
And there are projects like FediPact, explicitly opposed to having anything to do with Meta on an instance level.