Which isn't to say that we shouldn't criticise. Criticism is necessary. But there's a big difference between judgement and criticism.
Criticism seeks answers to questions, why something is the way it is, why a person acts in a certain way and so on.
Judgement seeks no answers, because passing judgement implies that you know all you need to know. You don't want to seek explanations for why things are the way they are, you just want to judge.
That's ultimately why judgement is the go to response for the morally self-righteous. It's easy. You don't seek any more information that might complicate things for you, you just label someone how you want and move on.
It's a crucial distinction. We don't ever know the full story, but if we don't ask instead of passing judgement we'll never find out.