I think we've all known this type of person. They're actually afraid of their own vulnerability and lack the emotional intelligence to express themselves without hurling hurtful words. They start making judgemental statements instead of staying on topic which naturally makes the other person defensive.

Unless you're taught the art of communication as a child, you're left to imitate the adults in your life who may have a low emotional IQ of their own. I always say, sometimes silence is the best defense.