They were locked out of more than the app store, including anything they stored on the iCloud account which is a separate service all together. It sounds identical to what happened in the story I linked to, although that one the person couldn't even sync their calendar. Maybe the $8 person didn't use that function & so didn't mention it. Or maybe it still worked, but it would be strange for all other things locked out to be the same but for that one thing.

Regardless, it doesn't make sense to me: Visa (Chase Bank) can't lock me out of a damn thing on on the phone I bought on Amazon. They can't even take the phone away: Most credit cards are unsecured debt, the phone isn't collateral that can be repo'ed. Store-branded cards, though also backed by a bank, are sometimes different and purchases are also security for the debt: one of the reasons I stay away from them. I live debt-free, have been fortunate to always be able to do so apart from a small mortgage, but don't really like the idea that a really bad run of luck could be compounded by having some of the things I need taken away from me as I try to dig myself out of a hole.

Why does it make sense you can't download FREE apps from the app store without a valid credit card? I get not being able to make purchases from the app store. But the app store is needed to get updates to banking apps, communication apps, etc... The price of that service is figured into the price of the device (you never have to purchase anything on the app store ever to use the app store)

If I owe the App Store money, it is not surprising to me that it refuses to work until I fulfill that debt.

They didn't owe the app store money.

Heck, they didn't even owe Apple money. They owed money to the bank backing the card: Goldman Sachs.

No, you're mixing up two cases.

Dustin Curtis claimed his Apple Card was the issue, but it wasn't. His not turning in his trade-in was the issue; that's owed to Apple directly.