I realize that, but it doesn't matter to the mistaken point the parent was making. If anything, considering the diminishing returns on IQ points or percentiles strengthens the point: by the usual argument that each percentile measures less real difference in intelligence (which I agree with), that means that the change in output is even more astounding! Going up 0.8% of the population yields you 3-500% increase in output, and this is in the part of the population where that IQ change ought to be least important. We ought to see much larger gains going from, say, 91th to 92nd percentiles, with less gains for each step upwards - but we don't.

No matter how you cut it, shifting less than a percentile and getting the measured increase is dramatic. (So dramatic that I can't help but wonder if there are non-intelligence explanations - could it all be due to Matthew or network effects?)