Yeah but then the league couldn't act like they're imparting an ESSENTIAL MORAL CODE which is central to a lot (like a lot a lot) of their marketing and official aesthetic.
You can bash each other until your brains are oozing out your ears and we'll pump you full of pain pills and booze so you can come out and be our cattle once a week, but if you do something bad, heaven help you, the NFL is only a place for the righteous brute.
There are, obviously, a lot of NFL players who are really nice people. That's just how the league tends to come across.