It's a good analogy - in the days before email, all you had was a username @ your BBS (Bulletin Board Server). You dialed into your local BBS's landlines with a modem - they usually had 2-4 numbers available, so that gives you an idea of scale. The BBS systems were federated so user@bbs1 could see and respond to the same threads as user@bbs2. It was nice - it worked pretty much like the fediverse actually - and the tone was similar.

The messaging systems on the BBS communities evolved into email and Usenet before big money came along and fucked everything up.