You don't have to be an asshole to get better quality work. But it's a great way to chase off talented staff that don't need to work with assholes.
The justification of abuse is just that - the desire to be abusive, and trying to make it okay by pretending it's necessary. Some people see this behavior and like it, because they too would like to be abusive or see people abused. But it has nothing to do with productivity. It's emotional diarrhea.