You talked about "the poorest who have cheap credit cards subsidize the richest who have the best cards". The point of the thread I cited is that in general credit cards make money from both poor and rich people alike, and make more money from rich people, and neither one is subsidizing the other in any framing of it. It doesn't matter whether you're talking points, miles, or any other form of rewards; there's no degree to which credit card reward programs have anyone subsidizing anyone else.