What they have in common with the herd that stampeded on South Street is that none of them can be held responsible for the extracurricular activities of the crowds they gather.
Kids run wild on South Street disrupting businesses and occasionally assaulting people. It's not the fault of the people whose Twittering drew them there.
Protesters on Capitol Hill shout racist epithets at black congressmen. You can't blame protest organizers if a few people do their own thing.
Dozens of businessmen take a loss when they are forced to shut down their shops on the first day of spring. Hey, nobody meant for that to happen.
A protester leaves an anti-Semitic note with a swastika on it at Rep. Anthony Weiner's office, or Rep. Barney Frank gets called "faggot" and "homo" as he walks past protesters, or some guy in the crowd spits at Rep. Emanuel Cleaver as he walks up the Capitol steps.
It's regrettable. But it's an unintended consequence of a well-intentioned protest.
Spit happens.
That's the resounding shrug of the suddenly impotent. Organizers can draw thousands of people together with a tweet or an e-mail blast. But they're not responsible for what happens after that.
You might buy that innocent act the first time one of these Internet-induced crowds gets out of hand. But it gets old after awhile.
You are painting them all with a broad brush, one woman e-mailed me after I said in a Feb. 19 column that kids who use flash mobs as a cover for their violence and vandalism should be "dealt with harshly."
Most of those kids didn't go to The Gallery to start trouble, she said. They just got caught up.
Tell that to the boy who got kicked in the face outside City Hall or the adults who got pushed to the ground as the crowd raced past them on Market Street.