I don't have the stomach to read through this entire thread. I think the gist of it is that mountain bikers are dicks and enjoy being dicks to one another.
The original point of this thread is valid. There's no need to be a dick and yell at people when you pass then. On the flip side, when getting passed, make some kind of effort to get out of the way. However, this is all situational. For example, on CBC, there's really no need to go blowing by somebody. Slow down, let them know that you're there and hopefully something works out in the passing department.
But I've been known to throw down a hearty "Get the fuck out of the way" on occassion. Examples - Let's say you're rolling down lower Bogeyman and there's people walking all over it with their bikes laying on the trail. Get the fuck out of the way. Have some common sense.
And A-Line. No offense, if you're a beginner rider and you're riding an "expert" trail up in Whistler that requires a certain degree of speed to clear everything, be prepared to pay attention to who is behind you and be really prepared to move over. But once again, there's no need to be a dick to somebody just because they're slow.
Anyhow, if you avoid the birthplace of the freetard (Mt. Seymour) I find you can avoid most of them. But with the annual summer migration up to Whistler, it's a lot tougher.