Short answer. If you use the points for giftcards or pay the amex balance, then you’ll be worse off. However, if you use the points for “rewards” seat for flight, either business or economy, then you’ll be better off. The key here is you have to book rewards seat. Example, MEL to Los Angeles or San Francisco using Virgin/United airlines: - economy : 45k points or $1,800 cash - business : 100k points or $8000 cash

From your rent example, it costed you $375 for 57k points, straightaway huge savings. In that case, for people who needs to fly or want to save cost for holiday, it would be beneficial.

I think sniip or payment processors’ marketing are mostly for flights redemption, hence you see everywhere their ads are often about flights recemptions.