There is no such myth. Nobody is surprised that you can say something about a distribution if you know some facts about the distribution. Using "single data-poi

There is no such myth. Nobody is surprised that you can say something about a distribution if you know some facts about the distribution. Using "single data-point" in two completely different ways is just bait and switch. Any data pertaining to humans would be a single data-point in the true sense, which in itself gives almost zero information. You can't compare that to knowing global properties of the sample or the distribution, it's completely different things.