Someone commented today about how a crowd has lower intelligence than the individuals within it. It’s no mystery. The reduction in mental acuity is a trait evolved in our hominid predecessors for hunting in packs, encircling game as a coordinated unit.
To encircle effectively, each hunter must adapt his movement to that of the slowest pack member, to prevent gaps in the circle. Pack hunting remains an inherited autonomic behaviour, and this is why the collective intelligence of a mob tends toward the lowest common denominator.