I remember a long Reddit post detailing how a slap (man on man) was the ultimate response and how the person being slapped would almost never fight back.

Where and who the hell said this lol?

I have seen people get bitch slapped by other guys, and they don't shy away. That is an instant reflex from the one getting slapped to smack the other dude back. It's a fight until someone breaks it up.

If I walked up to any of you and slapped the shit out of you because you were say being rude to a retail employee. Even though you're in the wrong, a person's irrational/emotional state of sheer anger is going to make them respond very violently, and hit back.

Only in certain circumstances depending on who slapped you would people back off.