I've been a member of many games communities over the years - clans, guilds, forums - but the one I remember most fondly was a server.
In my experience, those other kinds of communities could be great, but they were also more prone to politics, in-fighting, and collapse. This is probably owing to the fact that they are deliberately formed and their founder is normally present. A hierarchy is unavoidable.
The game server I remember best had an owner and operator - I'm pretty sure it was not an emergent growth - but I never knew who it was. I'm not sure if I ever played with them or not. There were moderators, but we were lucky in that they were kind, and concerned only with kicking the occasional cheater, spammer, teamkiller and playing the game with the rest of us.
The game was Counter-Strike. I played it every day, for hours a day, and a good server was important first and foremost because I had a 56k modem. Good pings were hard to come by. Initially I clung to this particular server because it offered low-ish latency and because it tended to have a couple of available slots in the hours when I wanted to play. But soon I was returning for the people. Play at the same time and place enough times in those days and you'd see the same names again and again. Slowly, you'd talk, get to know each other a little, and find a casual camaraderie.
I've been thinking about this today after finally going back to play some Rainbow Six Siege. I love the game, for reasons I've explained elsewhere, and my matches today were good. Not because I played well - I totally did not - but because the other players were friendly. The higher level players recognised that they'd been paired against a group of relative newcomers, they were encouraging, they told one player off when they gloated at winning, and it was the rare pleasant experience in online gaming.
This didn't take place on a server I can revisit, however. Like most modern multiplayer shooters, Siege relies on matchmaking rather than dedicated servers. And in most ways, I prefer it like this. Despite one or two great servers that felt like home, much my time in Counter-Strike was spent trying to join servers that were full by the time I clicked them, that lagged more than the server browser had suggested, which were full of cheaters, or which required the download of a dozen annoying custom sounds. Matchmaking fits much more into a life in which I have less time to play games, and less time trying to simply get into a game.
But I miss the ability to make casual acquaintances of those good players I encounter during matches. There is, yes, the option to add them as friends, to reach out and forge some greater social connection. But that's not what I want. I want to drink alone in a crowded bar of people who recognise me, and who I recognise. I want friendly hellos and silent nods. A friends list is entirely too formal, too much.
There was much hoo-ha when dedicated servers first started to disappear from the feature list for multiplayer games, and some still maintain it as an option, but you can tell it's a thing of the past. Soon most players won't remember why the option was desirable, and it'll likely disappear even more. That's a real shame.