Startup Idea : CrowdPayments: Earn credit cards rewards faster

Now a days every credit card has rewards linked to payments, some have minimum spend requirements to unlock points, miles, some have different categories for 5x points unlock. However the problem is that now everyone is approved for these cards, and those who are having one may not have so much need to spend.So how about building a payment service, which allows rewards credit card holders to pay for someone else's debts by doing a three way transaction. Rewards card holder (Person A) pays bill of person who doesn't have a rewards card (Person B). Person B pays to the payment service and receives 5-15% discount on the bill, and the payment service credits the amount person A paid to an online account, and since it allowed Person A to be able to make payments and earn rewards it can charge them 20-30% of the rewards share.There's another version where Person A pays for Person B's bills as a good will and doesn't get a payment back from the payment service.