People keep saying this everywhere in the thread, but it doesn't reflect my lived experience at all.
I remember being a kid of about 7 and noticing that a friend was doing some "supplemental" exercises in a workbook. I looked over his shoulder and immediately saw that he was doing them all wrong. The one question I remember showed a racetrack and asked which car would finish first -- the obvious answer was that the car with the inside track would finish first. I hadn't ever heard the phrase "inside track", I could just see, spatially, that the inside track was the shortest, because it was the smallest circle, etc.
This ability to just see patterns and connections immediately (or more quickly than others) multiplied by every single new concept or piece of data you see in your life sums up to a net advantage.
If you're somebody who just "got" the limit definition of a derivative the first time you saw it, can you appreciate that there are people who won't get it immediately, and won't see as many of the ramifications as you do? Can you appreciate that there are people who can see much more complex mathematical structures that would leave your head scratching, and "get" them just as quickly?
To say that:
> Problem solving ability and comprehension levels will only take one so far if they can't bring themselves to bury their head in a book, or sit in front of a piano, or shoot hoops, for the time necessary to master said subject.
is just not that useful, I'm afraid. If everybody reads the same books and takes the same courses, the more intelligent will more through the material faster and learn it better. The world is not fair and there are not mysterious forces equalizing everyone's performance.