It swings both ways. Groups can either turn into Mobs (read: Morons) or Hiveminds (Brilliance). It depends on what's going on.
For example: Riots. One guy throws a stone, soon 3 more do it. Then things escalate as people follow the leader.
For example: There's an "mmo" out there designed by folks who want to stop pirates on the oceans. They let people -- anyone-- civilian and military alike, to play it as either security forces (with all the red-tape there is) or the pirates. These players, who are sometimes lead by military folk, other times not, have come up with brilliant strategies.