You don't get to be the biggest bank in the US unless you are doing something right. What bank has a successful business model from giving away retention to people who would otherwise leave? The better plan is putting resources into making a product that people WANT. Capital One is more desperate to keep clients, so they will throw out offers. Meanwhile, people are signing up to Chase cards left and right. Why do they need to cater to people who are either trying to scam them out of the AF or won't use the product?
Besides, in today's age, companies should know that the internet will take advantage of anything they can.