Is it a good idea to limit a customer's credit card so that it can only be used on one user account? The user can have as many credit cards associated with their account as they like, but they cannot use the same credit card on a different account.
The idea is to reduce fraud. However, is this a meaningful concern? Would this move be an inconvenience to a customer who forgot his credit card and wants to borrow his friend's for a purchase? Is it the job of the merchant to build their own layer of protection against fraud, or should the merchant rely on the payment processor's own filters to protect customers?
This question might be better off on WebApps, but let know what you guys (and gals) think!