The parent isn't talking about not using banks. They are saying that using debit cards (or cash) to do transactions when you could be doing the same transaction on a credit card and getting free points is akin to leaving money on the table.

This year I made several hundred dollars worth of points for which I did not have to alter my spending behavior at all. I am buying plane tickets and staying in motels and filling gas and renting cars and eating out and blah blah, credit card or not, points or not. It's ridiculous to not want to get back 1-3% of that money as long as you have even a bit of control on your spend. If you actually have a decently paying job so that you don't have to rely on credit cards to borrow money that you can't return, it's perfectly rational to have credit cards and pay the points game.