As another commenter noted, this article doesn’t pull out clearly how this whole credit card reward scheme actually works. The Acquired episode does, by the end.
It works like this: the ‘luxury’ credit card providers, partnering with Visa, take money away from merchants in order to extract profit for themselves while keeping the credit card consumers happy. The merchants are pissed about this, and regularly make lawsuits to regulate interchange. The money extracted by the credit card companies and Visa causes merchants to raise prices for everyone regardless of whether they have a rewards card or use a credit card at all.
This creates in effect a massive money transfer from the poor, who do not use rewards cards, to the rich consumers who do. The Acquired podcast provides specific numbers on just how much worse off poor consumers are given this system, and how much the richest consumers benefit.
I come from Australia where interchange fee regulation tamps down on the kind of credit card mania and fetishism seen in the USA.