Oh, then thats why, I wonder why they have Mastercard/Visa/Amex listed as a checkbox when you click +Add Card:

By checking this box and entering my payment card information, I authorize my Payment Card Network (Mastercard®, Visa, American Express) to monitor and share transaction data associated with my registered payment card (including spending history) with American and its third-party service providers in accordance with the SimplyMIles® and AAdvantage Dining℠ Program Terms & Conditions and Privacy Policy. Learn More