What do Flash Mobs do?

So in class the other day, we were talking about flash mobs and what type of activism they were. I said it was a form of both Gladwell and Stone because people physically go to be apart of the flash mob, and flash mobs can be coordinated by social media and there isn't really much risk in participating in a flash mob unless it turns into a flash rob like in London and even like Philadelphia over the summer.
But the one thing that I believe I might have gotten wrong in our discussion last week is that people have reasons to participate in activism. But with a flash mob, I never have an idea of why and what the people protesting. It's difficult to know what the people represent in a flash mob because its dancing around and not discussing what problems they are facing, or what they are protesting.
And this is why I don't think flash mobs are useful forms of activism. It is difficult for people to understand what the flash mob is doing, so I think that really hurts the overall message that the people participating are trying to make. If people who participated in the flash mob stay after and discuss what they were doing there, I think that could help spread the word about their cause. But then again some people don't have a cause and just do a flash mob to do one, which affects people who are actually trying to make a statement with a flash mob.
In conclusion I do not think flash mobs do a good job of detailing what you are trying to protest or represent. But I will say they are quite fun to watch sometimes.