I see nothing wrong with it because it's the nature of the game. If I tell a guy to fill the alley at full speed, I don't expect him to get there and play patty-cake with the running back.
Why not have a reward system? A "big hit" is too subjective, so he said if you need to injure a guy. I really don't see why it's a big deal. Every player in the NFL gets some type of ding in every single game. There's not one guy in the league after week 3 that isn't hurt in some way. I think it's cool, actually. Go knock a dude out. That's how we play D.
To me, it's foolish of you to think this doesn't happen everywhere, or if it's not to the extent of paying players, there isn't one guy out there who isn't trying to get a knock-out hit on his resume. Tell me when you played in HS you didn't want to de-cleat a guy. There's no guarantee that he gets hurt, but fuck, if he does, I'm getting paid. I win twice.