Ken Clark has posted the top seven things he likes about shame mobs. Here's a taste:
5) Internet shame mobs weigh the evidence carefully and deliberately before attacking, so they only happen to people who deserve them. [...] 3) Internet shame mobs always make sure that the punishment is proportional to the crime.
There's a larger phenomenon here where problematic information spreads faster than the correction to it. If it spreads fast enough, then it can even pass a tipping point where it becomes very hard to get a hearing to object to any part of it. Everyone has already heard the idea from, well, everyone else, so they quickly dismiss anyone who objects without even really considering it.
The key to stopping such memetic chain reactions is to apply some filtering before propagating information that you read. It's still early days for the Internet, though, and we are all still learning to inoculate ourselves from being the wrong kind carrier.
There is some reason to have hope. Chain emails used to flourish, but are now mostly stamped out. In their heyday, 15-20 years ago, it was fairly common to open your mail program and see numerous messages that said something very exciting, and furthermore that the message should be passed on to everyone you know as fast as possible. Nowadays, the people I interact with just delete any email such emails. If an email explicitly says that it should be forwarded to everyone you know, then it triggers something like an antibody response. Such an email starts looking very bogus, and it gets deleted quickly and possible even flagged for followup by the email provider.
Intriguingly, people would likely not have developed that response had they not gone through the misery of dealing with chain emails earlier on. There are clear parallels to viruses and to building up antibodies!
Shame mobs are a place where it still goes on, though. I'm not entirely sure why it happens. In part, people just want to defend an idea, and they are happy to use real people as an example no matter the consequences. In part, people just enjoy being part of a mob. I hope that shame mobs go the same way as the chain email. We shall see.