Or else, more generally... people are usually rather terrible at separating out "your behaviour is wrong and needs to be fixed" from "you as a whole are a terri

Or else, more generally... people are usually rather terrible at separating out "your behaviour is wrong and needs to be fixed" from "you as a whole are a terrible human being". People often define their identity by their actions, and to claim that those actions might be problematic is to attack their identity. Even where blame is explicitly not placed on anyone, people tend to go on the defensive as soon as you point out that their actions have unintended or un-thought-of consequences.