I haven't been on INTPc much over the last few months. (I've been mostly bored with the conversation, honestly.)
I think most of the people are adequately typed. I think because of the medium there is simply a preponderance of 20-something INTPs who have never yet found a place where they feel at home. The behavior seems typical for people in that stage of development. [There are some older members who are better rounded and more emotionally mature.]
Eventually, hopefully, instead of fortifying themselves in, they will continue on their growth path and learn to accept the parts of themselves they do not like. It's just difficult because many of those parts (such as values and/or emotions) are the parts that others have expressed when abusing them or contributing to them feelings of inadequacy/difference. They need to pull away from those things first, to get a "core self," then learn to embrace them later. So INTPc serves a valuable role in that maturation process. I see all the "mistype" complaints here to be mostly exaggeration. (50%? Please -- give me a break! The descriptions here of IxTPs is yet one *more* large bias.)
I think a worse problem is the group-thought, where people feel compelled to fit a stereotype of what INTPs are "supposed to be." Because otherwise they'll lose their member's ID card and feel like they've been ostracized once more... and NOW where will they go? There are a few notorious people I wonder about.
But honestly, who even cares? People are who they are. We are not our type. Type is simply a paradigm used to explore the self and others. If they're mistyped, most of the time that has no real impact on anything, and they will figure it out eventually. I don't really see any more mistypes over THERE than I do over HERE to be honest.