The first part of your reasoning is correct, but the rest isn't.
First there's only a limited correlation between IQ and chess.
Second, I doubt you'll find many competition chess players in the ranks of what you call 'the brightest minds'.
Third, there are countries where chess offers more career opportunities, thus stimulating the development of strong players (eg. India).

Just a thought. Rating is a measure of relative performances, not absolute, so my rating depends on the strength of the people I play with.
Almost all amateurs play in the area they live, so they encounter only opponents who live nearby.
Knowing that there is a correlation between math/logical intelligence and chess, it stands to reason that the strongest chess players will have to be found where there are jobs for the brightest minds. And I'm sorry for you, politically correct crowd, but the average guy who works in investment banking is much smarter (at least as far as math/logic goes) than the average guy who shags sheeps in a godforsaken countryside.
So if you live in London / New York, you'll go against much stronger opposition than if you live in a small town in Wales / Utah. Thefore your rating would be greatly inflated in the latter case: even a mediocre player facing only bad players will be able to get his rating up.