I'd say they do interact pretty fluidly, in their boos and cheers. Sure they need to be primed beforehand, but when they all get together in the same place, then you get the self-reinforcing effect.

You could probably say the same thing about ultra-partisan websites. Luckily this has resulted in the GOP not even being able to run a competent negative campaign this time around. They are lost in their paranoid conspiracy-theory End Days melodrama, talking only to their fellow inmates, and haven't managed to get traction beyond the die-hard social conservative base, which is apparently all that's left of the GOP.

They're going for the emotional hit instead of trying to convince people who don't share their obsessions. Satisfying in the short term, but it'll probably lose them the election. What a damn shame.