Being a member of many miles/points dining versions of RN, I have lots of credit cards registered. As it's convenient to be able to move whichever card I want to use around sometimes, I just leave old (i.e. dead/expired) cards as placeholders. Recently, I've had a flurry of emails from various RN dining sites of this format:
Dear Kremmen,
Thank you for participating in [FFPname] Dining. Due to recent changes, certain credit cards may no longer be registered in our system and may not be used to earn [Airline] Points/Miles for dining activity occurring on or after November 10, 2012.
The following card registered to your account will no longer be supported:
Card ending in: NNNN
I don't know why they say "due to recent changes", because I doubt anything has changed. I don't know why they are bothering, as disallowing RN to use a credit card that doesn't exist has no effect on anything. They haven't actually removed them from my profiles, so the old cards still seem to do their job as placeholders to ensure that I always have 1 card registered per site. Maybe they will eventually be removed? But then what happens if that was your only registered card?