It makes sense to me when you see BankRate's explanation:
"We have been working with Bankaholic in a co-brand relationship since July and have seen first-hand the volume and quality of its traffic," stated Thomas R. Evans, President and CEO of Bankrate. "Bankaholic is ranked high in natural search for both deposit and credit card keywords. We believe their organic traffic will increase our deposit and credit card revenue, and with a high composition of free traffic, will help to improve margins," Mr. Evans added.
So they basically tested the traffic and it proved a purchase would be profitable.