I have observed this, too. I have wondered if the offender is looking for some kind of emotional response from their opponent. For example, I have seen parents argue with their kids and just when you think it's over the parent comes back with something else. It's like they can't be satisified until the kid starts crying. In my mind, I think of Roman gladiators. It is not enough to beat your opponent in combat, you have kill him even though he's beaten. It's brutal and barbaric and abusive, IMO. While this might be an extreme case, it's possible all such folks are looking for some emotional of submission.