I don't think that the INFPs are trying to be mean. I think, in their heads, that they are actually HELPING you by being harsh?Sounds very familiar on the unhealthy INFP side, although I do wonder if a fear of judgement or criticism is 'innately INFP in nature' as something more easily projected onto others (in your experience).
In other words, they are AWFUL at pointing out a flaw that needs to be worked on. They'd make terrible managers and leaders. I'm talking in generalizations, of course. Some INFPs would make GREAT leaders.