I mentioned Livejournal, Wordpress, and Dreamwidth. Yes, it was possible to get banned from these large hosts. But that was an extreme action, and the people with the power to do that were seen as quite distinct from the much smaller communities on the platform.
No-one at the particular social rank of a Mastodon server admin existed in that world - an elevated position that has powers that regular users don't, but nevertheless interacts directly with the user community. And that really does change the social dynamics a lot. (Some other platforms did have comparable roles - BBS operators, forum mods - and I don't think it's coincidence that they tended to have more drama)
I'm sure you'll have no trouble finding Mastodon servers where the admins go on stupid power-trips. But there's nothing in the whole system working against you just standing your own instance up, or, for that matter, running 10 concurrent accounts different servers, like RSS feeds in Google Reader. It just doesn't seem like a real issue, unlike on Twitter, where it is quite obviously a clear and present issue,.
I feel it's mostly not stupid power trips, but some more benign psychological effect: you left Twitter, set up your own Mastodon instance and told everyone how cool it is that the power to police your community (your safe space) isn't in Elon's hands, but in "ours".
Now some trivial fight happens on your server, or a misunderstanding. You could sit back and observe the situation for a bit, but damn, you went this whole Mastodon route, so you can finally act! The pressure to act is immense, even it it may be self-imposed.
Now add all the other people who feel similar pressures and are therefore quick to call you complicit. The post is there, what else do you need? Of course you must ban, de-federate, whatever. Now! That was the whole point of it. Even if nobody actually demands it, you can imagine it quite well. Better act before someone calls you out.
How did people in IRC handle it back in the time? By having a mostly homogenous group of users?
No. IRC was also a sort of global namespace. There's no such thing (that I can see) in the fediverse. Handles are closer to RSS links than they are to Twitter accounts, and the tooling just blurs the difference.
"Better than Twitter" is a very low bar, certainly far below "social network I'm interested in using".
Standing up a private instance is possible but not yet easy, AIUI; you need a server running 24/7, you need your own domain, the mainstream server software can't currently be used with SNI-style shared hosting. I don't know how good the client support for multiple accounts is, and even if it's good, it seems to rather undermine the point of a federated social network - at that point I might as well use old-school forums via something like TapaTalk. Possible is a good first step, but if the system isn't designed and focused on that kind of use case (and the fact that it's not built as a pure P2P system suggests it's not), then it's never going to be easy, and that matters.
No-one at the particular social rank of a Mastodon server admin existed in that world - an elevated position that has powers that regular users don't, but nevertheless interacts directly with the user community. And that really does change the social dynamics a lot. (Some other platforms did have comparable roles - BBS operators, forum mods - and I don't think it's coincidence that they tended to have more drama)