I agree with the majority of your post. But, I do, however, know from simple observation, anecdotal as it may be, kids and parents do get humiliated and upset. We've all seen blow-ups at youth tourneys; getting tossed around by another human being is a pretty personal thing. And, not every parent grew up as a wrestler or even an athlete; nor do they all have the "fight through it" mental model.
Having that life experience is good thing, and I am absolutely on point with you, but the gist here was about about retention and keeping them around so they learn that focus. I certainly know every kid has to go through it, all I am saying is when it happens they need more attention and awareness than the better or more experienced kids. And it doesn't always happen. And, retention in any context is built one person at a time.
As an example, we both watch and admire coach Red and his remarkable energy. That guy makes it a point to get around to every kid in that room every single day (and nearly every drill or go). Every one of them gets a personal conversation and a little of his "love." He's a great example of what I mean.