I've always found that the communities with some sort of modest barrier to account creation have been the most healthy.

I don't like gatekeeping or garbage like that, but it helps when there's something in place that limits how easy it is for someone to just create a new account.

I think people are more likely to put thought behind their actions when they know their account is probably the only one they're going to get.

One example of this would be the Pure Pwnage forums. There was a normal, public forum which was full of the exactly the type of bad behaviour you'd expect, but people who paid to get custom dogtags (a piece of merch) could access an exclusive part of the forums for "Gamer Army" members.

The concept was sort of silly and was really just a way to support the creators of the show, but it resulted in a much, much more welcoming and friendly community.

Of note, the number of people who were openly female was far higher inside the GA forums—I'm sure that plenty of users of the general forum were as well, but gamer culture back then was even worse than it is today—and the same ended up being true for folks who were gay, trans, etc.

This GA group also had a smaller number of active members. While the total number was something like 2000-2500, I think the active group was about 50-75 people. With that number of active users you could actual get to know everyone on a more personal level. It wasn't like the relative anonymity of the average "twitter friend".

We also hung out primarily in community run voice chat servers—this was pre-discord, so we used software like Ventrilo and TeamSpeak. Voice communication brings a whole new level of understanding which I think also made a big difference in how close we all became.

When I look at the communities that I have been in for a long time—and which seem the most healthy and mature—they all have these three traits:

* something limiting account creation
* under ~100 active users
* prevalence voice communication