For example, a loving father thinks he's doing his son a favor and manages to smuggle his son on the front lines a box of hydra-shok, or black talon ammo for his side arm. If anyone in his chain observes him possessing that ammo, he can be charged for NJP; if he manages to use that ammo in combat and its revealed, we have an international incident, and he'll be court-martialed, his CO relieved, and million$ in reparations will go to smoothing over the tenuous relationships necessary for victory. Don't think that's happened?
If you're thinking solely from the perspective of survival, you'll say this is crazy talk. If however you follow what JASmith was saying, victory is not contingent on extermination of the enemy - despite how you might feel. We could not afford to do that more than once, and we'd be the pariahs of the world. The ensuing isolation would be the opposite of self-regulation and control. Victory is complex, and the way we (the USofA) fight is with honor, so that we can take pride in ourselves at the end of the day, and we've said that with honor means we don't use certain types of ammo.