I was struggling to wrap my head around how federated social media works until I realized that email has basically been doing the same thing for 30 years. Different email servers are like instances of a federated network. You can send emails to people from within a single server or you can send emails to people on any other mail server. Your email address is a username followed by an ‘@’ and the server address, just like on Lemmy. Email is a decentralized service I’ve been using the whole time!
Google bought the company Deja and got their software, which turned into Google groups, and also got their Usenet archive.
They didn’t buy Usenet itself (which would be like buying “email”), and it is still very much alive, but it has changed, and most people have moved their preferred place to have discussions elsewhere.
Note: I was going to say “would be like buying a cloud”, but Google Cloud is a thing, so…yeah.