Reasons why I like systems that have rules for this sort of thing.

"Sure, you can torture the captive. That's a rank 8 check against Violence, so go ahead and roll. Oh, you don't want to risk any mechanical consequences for your horrible actions? Ok then"

I feel like there's a lot of overlap between powergaming min/maxers and war crime doers. It really keeps players in check without having to resort to hand wave-y deus ex machina like "it turns out the bartender is a level 20 barbarian lol"