Paraphrasing a lot, I think the advice is to have one credit card for scheduled payments and things, and not take that out of the house. That way if your out and about card gets replaced, you won't need to go through and update all your scheduled payments.
I can't be the only one that uses my once-every-18-month credit card cancellation to help me track down the services that I forgot I had subscribed to.
Unless you're dropping the account completely, it's not super effective, because card issuers participate in services to update your subscriptions to newly issued numbers.
