Exactly, several studies have come out corroborating that study that said eating boogers and bugs and dirt and whatnot as a kid boosts your immune system.

But since people still perceive it as nasty, they still shun the practice. Same as with drinking former waste water, even if it properly treated and completely safe. Hell, 99.9% of people (in the so-called "first world") think the water in the holding tank of your toilet (that is literally just regular uncontaminated tap water until it is used to flush waste) is nasty and won't drink it.