Nice to hear from you :-)

At the very least, if there really are people of that cognitive level running around, then the rest of the world is doing an absolutely terrible job of extracting information and value from them, and they themselves must not care too much about this fact.

Yes, I think that this is what the situation is.

I'll also say that I think that there are very few such people — maybe on the order of 10 who are alive today. With such a small absolute number, I don't think that their observed impact on math is a lot lower than what one would expect a priori, and the prior in favor them having had a huge impact in society isn't that strong.

More plausible to me is the hypothesis that the best mathematicians are within the same 5x limit as everyone else, and that you overestimate the difficulty of performing at their level due to cultural factors which discourage systematic study of how to imitate them.

"The best mathematicians are 100+x higher in intellectual caliber than I am" and "the difference is in large part due to cultural factors which discourage systematic study of how to imitate them" aren't mutually exclusive. I'm sympathetic to your position.

What do you think the reaction would be?

To change the subject :-)

How many times do you think such a thing has ever been proposed, let alone attempted, by a serious student or (even) senior researcher?

Basically never.