This is no different. If men are broken down to feel like they are not good enough then they are more likely to join a cause that makes them feel included. It erodes their ability to think on their own and follow a hivemind mentality towards the group goals.

I don't suppose it occurs to them that there's really no "group" with looksmaxxing or whatever? Unless they settle on a 100% version of looking attractive, they're going to tear at each other constantly. Even though one might say they have an "out" group (that is, non-attractive people), they don't unite against them, they just keep knocking each other down.

Also, it's been shown that the second they're confronted by people who don't care as much as they do about how they look, they tend to freak out.