Occupy was doomed when they let Ron Paul supporters in. Before that there was a chance that liberals, Marxists, anarchists and DemSocs would find common ground but the AynCaps destroyed that.
ETA: There’s nothing wrong with having spokespeople going on stage or speaking to the press, but they shouldn’t be more than that. Leaders can be a weak point, plenty of movements have fallen apart after the arrest or murder of a leader.