Honestly, I agree. Bullies and assholes only continue because there are rarely any consequences for their actions, and because in some cases society will bend over backwards to help them to avoid the hassle. If companies are terrified to ban customers, and will even give them discounts/free products to get them out of their hair, what incentive do these customers have to act like decent people?
On the other hand, if the bans start coming and everyone enacts a zero tolerance setup for abusive customers, they'll realise their mistake soon enough when half the town doesn't let them shop there. Companies just need to put their workers first, and realise that assholes are not valuable customers.