You don’t have to spend the rebate at Costco, you can get cash at a register or at the service desk for high amounts.
This is debatable. The most valuable part of airline credit cards is the signup bonus. After the signup bonus you can’t get much value from the points received for regular spending. For most people, especially those who don’t travel first/business class, a straight up 2% cash back credit card would work better than any airline card. Airlines have an established history of regularly devaluing points, so collecting points is also a fool’s errand.
That’s 20% back in SYWR points, right? It’s not a true 20% back due to limited redemption options.