Another interpretation is that the credit card balance is charged interest but the monthly payments, which are paid using the card, do not have interest applied. Which sounds accurate and not necessarily misleading, though there's an argument to be made given they market the card so heavily. I think the confusion stems from the situation of making monthly payments with a credit line that also expects monthly payments.

I agree, that is very likely where the confusion comes from. It would probably be better if they kept the billing separate even when it's on the same statement.

I hate to jump directly to assuming nefarious greedy corporation, but obscuring the monthly installment by paying it with the credit card does strike me as a deliberate choice. I guess CFPB agrees.