If people are making a large number of similar jokes, then that's another sort of group think.
(nods)
It's sometimes helpful to draw a distinction between "lots of people do X" and "nobody is allowed to do Y."
The groupthink Alsadius is positing is the latter; it involves nobody being allowed to express certain sentiments. As I said, I don't see where he's getting his confidence that this is true, as I don't see much compelling evidence for it, but accepting it as a hypothetical I agree that the "safety valve" theory he's talking about follows from it.
The groupthink you're positing is the former and suggests different tactics.
As Multiheaded added, "Personal is Political" stuff like gender relations, etc also may belong here.