You make a good point. I once bumped into an IQ test that was asking questions about baseball rules.Respectfully, I disagree (On the IQ statement you made, not on the snowflakiest snowflake).
I was going to chime in on saying that if someone were to go off an IQ test's standards alone, then ESFJ's would typically have the hardest time of any MBTI.
The following is why:
(Since I still can't post links , I'll mention that the following quote is from oddlydevelopedtypes[dot]com under the INTP IQ section)
"I.Q. tests measure abstract reasoning skill (Intuition), the ability to solve problems alone and silently within your head (Introversion), the ability to think objectively about non-people oriented problems (Thinking), and flexibility in solving never-before-seen problems (Perceiving). There is no fresh news here; all of this is predicted by type theory.
And indeed, the more of those preferences you have, the higher your score on an I.Q. test is likely to be. Introverts tend to do better than Extraverts. Intuitives tend to do better than Sensors. Thinkers are slightly preferred over Feelers. Perceivers have an advantage over Judgers. These are average trends, of course, but they all add up to a clear ranking based on personality characteristics.
For this reason, INTPs are predicted to do the best of all types on I.Q. tests."
Keeping in mind that the IQ test is just one form, and one of the oldest forms, for measuring certain kinds of intelligence. If someone were either completely old fashioned, or if they were silly enough to believe that an IQ test is able to predict a humans full intelligence, then they make the wronged assumption that ESFJ's are stupid (When in fact, they're not). That said, I really wish they'd come out with some other solid tests focused on Interpersonal intelligence and such. I'd love to improve upon my horrid people skills.