I'm surprised you are saying this, and think it's your bias but perhaps the bias is mine - I'd expect them to be extroverted more, to be honest, but there could be a high number of us around here that are I, as long as they are on the judgment side.
INTJ / INTF types are VERY prevalent in debate societies, nerds, philosophy clubs, libertarians, etc.
I would expect the good majority of us are in this category.
The introvert / extrovert thing is often misunderstood.
Some people believe introvert = "shy" and extrovert = "fun"
It has nothing to do with that, and you cannot tell whether someone is an introvert or extrovert by talking to them.
Introverts are *introspective* ie thoughtful, and are
most relaxed when they are in a quiet place, or at home.
Extroverts are the opposite, and are
energized by large crowds and noise.
I would say the very fact that we are online, alone, typing to strangers on an internet forum, makes us more likely to be introverts than extroverts.
The best way of telling which you are, is
how do you prefer to *relax* after a long week at work?
Do you want to go to a noisy bar or club, or do you prefer spending an evening at home?
(Personally I hate going out on Fridays--I stay in and relax. Saturdays I might be out doing social things all day long, and hitting a bar or brewery at night). ==> Introvert.
You can be a very outgoing introvert (that's what I am) or a very shy extrovert (I dated a girl like this and it was horrible for her because she was socially awkward but she craved social events).
@Samseau I've never heard of someone being neutral on the E/I part, but I imagine you can either take or leave large crowds, it just doesn't matter much to you.
Anyway, I think this stuff is interesting. It's been a few years since I've tested and I wonder if I've changed any. My world outlook is far different today than it was a few years ago.