The comparison to Paypal is funny. Paypal has decided that I don't exist, or, if I do, that I'm somehow ineligible to buy things through Paypal using my credit card.
Buy. Things.
If your site does payment processing through Paypal then, through some accident of account processing or technology or the history of my account, I can't use any of my 3 payment cards to buy what you're selling, because Paypal believes it needs to (for reasons passing understanding) link directly to my bank account before any card with my name on it can be used through Paypal.