It's called PCI compliancy. They have to have some form of account to encrypt your credit card information, and for tracking purposes. Beware of any company that takes credit card information without creating some form of account for you. If they get hacked, they will have all your credit card information.
If you think it was hard for you, imagine what they have to do just to sell things online to allow you to pay with a credit card. I work for a company that does a lot of online and catalog sales, so I know what is behind the scenes.