I think it's the diversity that keeps this forum so appealing. Those trouble makers who might foul an otherwise decent forum, find their audience here, in a specific forum, or two.
We have a huge range of available "communities" within this place, that there's a place for everyone. There's the "elitism" of the specific manufacturers forums, where fanboys can fly their flags, there's Whine and Cheese, where the attention seekers can get their fill, and get their just deserts. There's the "Front Porch" crowd over in Traditionals, there are the Professionals in the Custom forums. The Intellectuals like to hang out in Political. Even a place for the young-uns over in the Balisong forum!
Of course, these are just stereotypes and do not universally apply.

I find I hang out in different forums, depending on my mood, and interests at the time.
There's a place for every kind of knife appreciator here, and you'll see those who never cross over to other areas, but that is what keeps us civil.
Kudos to those who are universally pleasant, wherever they hang out. I appreciate the hard work the Moderators do to keep folks aware of the rules. I also appreciate EVERYONE who contributes to this place, in a constructive and civil way.
I stated this somewhere else recently. This place is my home, when I'm not with my immediate friends or family.