I never played football but I did play a bit of little league baseball. I won't claim my memory of that time is perfect, but my basic memory is:
a) The sons of coaches were almost always the pitchers. Pitching was the only thing I was actually any good at so this annoyed me a bit (I would not have become a good pitcher at an older age, but at that age I was pretty good, which basically meant I could throw a strike with reasonable confidence).
b) Traveling all-star type teams weren't exactly the meritocracies they were supposed to be. Those teams always had lots of pitchers for some reason. And all extra-season playing opportunities (camps, other traveling teams, etc.) required significant financial support.
Of course this basic framework isn't unique to sports, and the details aren't quite the same as described about football quarterbacks, but in sports, like in just about everything else, some people have more opportunities than others...