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!
I’ve been told people under {some age, maybe 35 now?} only use e-mail at work. I’m not actually sure how this is really possible, because you need e-mail to get all those “social accounts”, as well as a lot of Government stuff (like DMV stuff), Banking and more, but it’s what I’ve been told.