> what’s the rationale

Their mega high risk - high value gift cards are effective for laundering stolen/fraudulent credit cards. Buy a $500 gift card with a stolen CC and sell it on FB marketplace for $400 - you’re up $400, the buyer saves $100, Apple get paid by the retailer and the CC company are (likely) on the hook.

Of course the actual solution here is _don’t sell high value gift cards_, or require the Apple ID email at time of purchase/activation of the card