@JTE There's one important thing you're missing about federation: Each instance only grabs exactly what it needs from every other instance. Following a dead user doesn't get you everything else they have.
Think of it more as e-mail rather than bitcoin.
@KS I have no idea how to find new people on this thing, then.
Other instances are generally opaque as all heck unless you make an account there or scrape its recent public history.
There is no "find other users like this one" stream like on any commercial socialization software, so the only way you can even see I've said anything is to happen to be following someone when they re-toot me? Instead, there's a weird and userbase-obfuscating federation system.