But if we don't separate ourselves from others and point out their flaws to make ourselves feel superior, then we'll have to deal with our own flaws and insecurities.

I'm being sarcastic, but it's basically true. Obviously, the scientific, medical and advertising communities want to know the averages so they can work with those. But from a social perspective, we want to point out other's flaws so we can feel better about ourselves. How better to direct attention to yourself than to show everyone around you that the other person isn't like you? Artificially creating an "us versus them" situation.

If we can prove we're "better" than someone, more like everyone else, "normal", then everyone will like us better. It's easier to hide behind the faults of someone else than to try to correct them within ourselves.

Atisha's advice to the Tibetan people