I don't know if it's the INFJ part, or the Facebook part, or both...but seriously, they just make me want to run screaming back to TypeC.
Some interesting things pop up, but I very much doubt that a lot of the people in these groups are INFJs. The criteria seems to be "I view myself as a special, wounded person, and I'm going to be terribly precious about everything." Taking offense at things that no normal INFJ or just PERSON should be taking offense at. Discussion of other types always seems to cater to the worst stereotypes. Etc.
I guess Facebook attracts a lot of silliness, but I wonder if it's also just the fact that too many people of one type - or too many people who believe themselves to be of one type - in one place at the same time is not really a good thing.
Maybe if I were a type 4 INFJ I'd have more sympathy.