Because scams are a threat to the serfs, and people spreading the truth about global events and issues is a threat to the powerful. That's why I really don't bag on "slacktivists" anymore. I'm not saying there isn't SOME truth to the notion that people reliably pick the one kind of activism that doesn't require getting off the sofa, it's a fair critique. However even that kind of activism is now heavily policed around the humanitarian crisis that won't be named.
If it wasn't a threat, they wouldn't police it so hard.