Some forums let you pay to regain entry, others would downvote but not outright ban (like Slashdot).
Banning was practically impossible given dynamic IP addresses and dial-up.
The internet was much smaller, its users more technical, and its software much more bug-filled. It was entirely possible that banning someone would lead to them exploiting your server and taking it offline. I witnessed that happen several times.
People focused on mostly getting along. Nobody was sensitive about the bullshit we whine about today.
It's also interesting that the zeitgeist at the time favored conservatives, so liberals were the then-staunch supporters of free speech. (Remember the Church of Satan?) That's completely reversed now.
The internet of today is so incredibly different to the internet of the 90's and early 2000's. Despite all we've gained, we've actually lost a lot too.
The Fediverse is the same way: You can have the wild west, but much of it is kept separate with active defederation so you may need to find smaller instances, run your own or simply have a second account. That doesn't mean it's not there.
The internet was open and unmoderated when nobody was abusing it. Once people start abusing it, it will be moderated. It's unavoidable.
> It's also interesting that the zeitgeist at the time favored conservatives
I don't think that's true. The 1990s saw the rise of conservative talk radio and of Fox News, but they weren't as dominant as they became later, and the 1990s were a pretty liberal time in much of the western world.
> liberals were the then-staunch supporters of free speech.
Still are. But even then, they didn't tolerate intolerance. It's just that at the time, intolerance was universally seen as bad, and not central to a rising ideology as it is now.