@futurebird The why is that their whole thing is signaling loyalty to the group, so that if you’re a member you are protected, and if not you can be openly attacked.
It actually works better if the signaling mechanism is something that puts your safety at risk, or stating as factual something that is clearly nonsense. If the mechanism were something that was a sensible thing to do anyway, it wouldn’t really mean anything about your level of loyalty to the group.