They look like it, but its some sort of emergent behaviour,
I agree with this assessment. It almost feels like a hive mind; I’ve dipped into the peripherals of online mobs before, and have felt “hey, this action is a good idea” thoughts enter my head unbidden. I’d probably participate in such things often, if I didn’t have a set of heuristics that (coincidentally) cancels out most of this effect, and a desire not to associate with the sorts of people who form mobs.
If the barrier-to-entry is increased to “requires two minutes of unrewarded drudgery, where it’s not intuitively obvious what needs to be done” in such a way that a short, well-worded “mob instruction” message can’t bypass the effect, it’s unlikely a mob will form around such actions.
Incidentally, I wonder whether programming for the mob is a field of social psychology.