first: research ad hominems, seriously. it's really fundemental to rational thinking, and their are INFJs who are competent at rational thinking. if it wasn't so creepy i would give you addresses. second:
which sort of makes this:
and no, not only because your giving up on an idea (that is actually partially inspired by something you've said btw) that could potentially help you in life and save your loved ones a lot of pain just because you jumped your conclusion of my understanding of the situation, but because that kind of thinking in itself is integral to the doorslam phenomena: judging other's character for what you do yourself.
now, this is going to seem a bit ugly - picking a case to disect - but fidelia's example is the most easy to demonstrate:
i don't know her well enough to know if it applies to her fully, but the chances are very good that it does - because generally INFJs tend to be very private with the information they will let themselves divulge about themselves and as people who often take the social role of providing council, it is nearly unavoidable that they will find themselves in situations where they will avoid giving away information that other people would find important. in other words, lying-by-omission. yet in her doorslamming story, the reason she doorslammed her ex was him doing something that she probably does herself often - lying by omission. now, i'm sure she score a lot on those to get an INFJ, but where was the Ni-Fe then at that moment? where was the room for reasons, circumstances and justifications from his perspective that in all probably she lends herself? my answer is simple - it wasn't there.
yet the most common sentiment seems to be that the person is abusive. now, the world is full of abuse victims, but where are the abusers? do you think they aren't saying it because of shame? maybe a few, but i am betting most of them have no acknowledgement of behaving abusively towards others. they may even have very particular relationships where they did, and many where they didn't, all together reinforcing the classic line of a beating spouse - "look what you've made me do".
what differentiates them from others is that they don't ask if their behavior is abusive, they don't look into the other person's perspective. when you find yourself in a situation you can't do that, the judgement you need to act on isn't of someone else - that's percisely what stands behind abusive mentalities in the first place - rather, it's of yourself, and since you can't doorslam yourself you better figure out a way to work on it. being aware of this would help you do so. choosing whether to use it - ofcourse - is your own damn business.
and whether it is a staple of the INFJs or not, it would explain a lot, because it becomes so much easier to have high ideals for people when you ignore whether you fullfill them yourself.