Especially intelligent people all eventually end up taking real IQ tests like a Weschler's. Which breaks it down into a dozen or so categories.

What you're talking about is crystalized knowledge which is just a tiny slice of the pie and incredibly hard to measure. Making it the least important

On the Weschler it's just trivia questions and you keep going till you miss 3. Or spend ~2 hours (just for this subtest) answering every question even if you're wrong 66% of the time. Like, it's literally the hardest to measure because of that, and because it's the one (obviously) most likely to be effected by education.

Like, one of the questions was/is "who wrote To Kill a Mockingbird". Every American was exposed to that information as a kid, so a younger test taker has a better shot at remembering, but wouldn't have been exposed to other knowledge yet due to their age.

But that's probably the biggest difference for especially intelligent people: everyone else still thinks of IQ as a single number. Two people can have the same sub score and drastically different overalls, or the same overall but a completely different spread on the sub scores.

If you're looking for the most important sub score, you're gonna want something like working memory or processing speed, but even those conflict. If your brain is running at 120mph, keeping something in your head for 2 minutes while doing something else is harder than someone's brain running 30mph due to difference in perception of time.

Tldr:

Intelligent people realize overall IQ just isn't that important for intelligent people.

The vast majority who get "too high to measure" never take the more specific test that could give them a more accurate score. 3+ standard deviations above 100 and it just doesn't matter anymore.