>> It's not quite as hostile an approach to community building as experts-exchange, but it's close.
I understand there is a tradition of slamming EE when discussing SO/SE, but "hostile" seems a stretch, at least in my experience.
I've found few technical forums online or in "real-life" that were as welcoming and community focused as Experts-Exchange.
Beyond the obvious in-question discussions, EE members communicate directly through email, instant messaging, phone calls and face-to-face meetings. EE corporate sponsors periodic meetups between administrative staff and members.
I've participated fairly regularly over the past few years and people have contacted me directly, off-site for assistance with confidential issues that couldn't be easily posted in the form of a public question. I've been made job offers, did a little contract work and simply chatted about UFC, scuba diving, beer, kids, photography, work, movies, etc.
I've had the opportunity to meet a few of the members face-to-face and, while I don't know them all well, I can honestly say they've been consistently friendly and helpful online and in-person.
Also, beyond just the "warm-fuzzy" of good-people. EE is a commercial site. The only way it can pay for its servers, employees, bandwidth, storage, etc. is through its community of customers. Sure, some people have been unhappy and left but that will be true of any service. By and large though, people come to EE and stay. If EE was truly a hostile environment it's membership base would have shriveled up years ago and the company would be gone.
Going back to SE/SO or any other Q&A forum the fundamental design of all of them is ask about something fairly specific and get answers about your topic. Comments that don't address the topic itself, no matter how insightful, true and possibly helpful they are are, by definition, off-topic and don't belong in that thread.
If I ask how to change the belts on my car and you give me an awesome recipe for apple pie, it's just not helpful and your comment should be deleted, voted down, masked, moved to new thread or otherwise discouraged/eliminated (the specific action will depend on the forum.)
The forum, as a whole, may be open to any and all discussions, but within the context of any one thread there is either implicitly (by nature of the asker's intent) or explicitly (in member agreement for a particular forum) a rule established that comments stick to the topic of that thread.
Community can actually be self-destructive somewhat in this regard. As members become familiar with each other there is often less inhibition to interject side-comments for humor or nostalgia of past discussions. Strangers, without that sense of familiarity, may refrain from joining the peanut gallery and instead stay more formal.
All Q&A forums want to stay close to the top of the Google lists. Maintaining good signal-to-noise ratios is the only way to do that. If that means truncating a few tangents in order to keep threads in line, that's good for all. As others have mentioned, the members are at the site because they like it. If they can't police themselves in such a way that the site can prosper then others must do it for them. That's not just SE/SO or EE or similar sites. The same applies to all information providers.
Keep the content useful and on-point and it'll rise in popularity. Let it drift an so will the rankings.