So people are finally getting smart and realizing the best way to rob a place is by a flash mob. It effectively neutralizes any defense a shopkeeper or passerby might have. Sure, call the cops. By the time they arrive, the mob will be gone with just about everything they wanted. And with so many people robbing you at once, remembering details about anyone in particular becomes difficult, severely reducing the likelihood anyone will be prosecuted for the crime. Second Amendment arguments don't help you much here, either. One armed clerk vs. a mob which may or may not have weapons? In that situation, you keep your gun hidden and hope to god the mob just goes after property.
That said, if this really goes viral, you'll see very severe restrictions in our civil liberties, in particular to privacy in electronic communications.