I guess it isn't stupidity that comes from a lack of ability, but from a lack of experience or a lack of ever trying to do basic things because they've excused themselves from learning to do them. I think limiting yourself choosing only the intellectual over the practical is "stupid". It also ties in to what has been mentioned before, not considering other viewpoints (as opposed to being clinically unable to learn these things).
Of course people like that are still rare amongst NTs in my experience, but they're out there. Anyway that's just my take.