I think there's a very similar dynamic at work in politics, where people self-identify as a particular party or supporter of a particular ideology, an then take any criticism, however mild" of that party or ideology as a personal attack upon their very identity.
Yes, I think this unfortunate tribal protection trait is built into human nature. In the past it may have helped, but we end up forming (and violently 'defending') tribes around random things. It seems religion, sports, politics, etc. play on this instinct.
