It’s about being in the in group. As much as they claim to judge others on their actions and character, it’s actually whether or not you are a member of the in group. Anyone in the in group is automatically “one of the good guys” and can’t be evil. Same reason they call Republicans who oppose Trump “RINOs” to imply they were never part of the in group to begin with. They are impure, cast them out! They must never admit that the in group can be wrong, fallible, or the bad guys.