I would venture to guess, at least from working the Hunter Site In at our club, that most or should I say the average hunter does not load their own, but purchases ammo. They get what they get and consistency is not what they get. Sure they will buy ammo that says, "Match" or "Competition" but most likely will shoot not appreciably different in their gun that the low priced ammo on the shelf.
It is sad too, because a hunter needs all the help they can get:
1) they rarely know the exact distance to their target
2) the target is constantly moving
3) they most likely do not have a dope card or had spent the time to site in the scope to the distance they are shooting
4) their ammunition is rarely consistent making the chance of hitting their target even harder
5) don't shoot enough, maybe 20 rounds a year, if that and only a week before hunting season, so have little experience or muscle memory to support consistent shots
6) and last but by no means least, don't have a clue how to use their scope or rifle