I am going to be stupid and argue about the definition of stupid for a bit
LOL.
I've definitely met iNtuitives I would not consider smart. Most have been ENFPs, but ENFPs are the iNtuitives I've come across the most IRL. I knew an INTJ who was not that bright. He was good at math (but not in any other academic area), but otherwise a bit slow, and completely out of touch with reality in a way that made him seem dull-witted over all.
I would be cautious about classifying young INTJs as stupid, as they can be decidedly..weird and obtuse and engage in the Ni ranbling...I'd almost argue they are still building contexts to evaluate the world, thus they really begin to shine once past 30...
When considering EXFPs, when young, you are dealing with pure perception-action and speech before thought-the only thing holding it in check is a pretty gooey Fi. Thus they wonder around trying to "feel-in-the-moment" to solve logistical problems and can be TOTALLY oblivious. I have no idea how my 15 yo ENFP son has survived this long....however by about 25 or 30, most enfps have a bigger Te toolbox and can be more rational.
Is this stupidity that one grows out of over time?
If it helps, I'll use personal examples of stupid people I came across in high school: lack common sense, low vocabulary skills, lack general knowledge, inability to connect the dots more quickly without being told a step-by-step process:
For example, I knew a girl from my high school job that when I taught her how to make hot dogs (simple process: oven -> set for 15 minutes -> bell rings --> take out, throw on grill -> setup buns), she still needed me to actually tell her to "take out" the sausages from the oven or else they will burn, throw them on the grill, and finally set it on the buns. When they told me to grill hot dogs, all I needed was the last step (setup buns - which I actually inserted during the 15 minute wait).
These are people I think are "stupid."
Whenever I try and give my ISTP ex instructions, he starts getting really pissed at me. When my enfp friend tries to give directions to her INTP husband he gets really pissed at her.
In both cases, we give the level of detailed instruction that your hot dog girl needed-which a Ti dom does not want or need, as you guys follow a natural Ti path based upon "logical principals of how things work". Yeah, EXFPs do not come equipped with said "logical principals of how things work", instead having focused upon developing "reasonable values about how people feel".
I have actually frusutrated one INTP, as I asked for very direct directions regarding feedback they had for me-since it was a very direct request for change, I requested very direct instructions for change. They asked if I could not "think for myself". When I pushed further, they said since they thought about things based upon logical principles, it was hard to provide this direct "Do this..." sort of feedback....
so maybe hot dog girl is stupid-but maybe she needs to hear things explained in a way that her mind can grasp-which may be very different from yours..? Just tossing the thought out for consideration.
Actually, the opposite. I sometimes think people think I'm a bit slow at times because I usually pause, mumble, or use too many words for a sentence, but when I write to them, it's like I'm a completely different person! I think intelligence is superficially tailored toward Te since they are a lot more...eloquent [on the spot].
Ah, My very favorite INTP has had many people think he is a stoner, given his speech patterns can be very paused and slow. Very brilliant guy-however he did come to work once and tell his he was very sick. It turned out he made mashed potatoes but didnt cut off the little eye-roots, as he didnt know they are a bit toxic. I do adore him a great deal.
He now has his dream job which involves writing up patents and shoving them under the door to somebody else to implement.