Q: WHY is a credit card required?

We've used a debit card (backed, of course, by a credit card provider) to purchase through iTunes and App Store.  To date, that's been acceptable and and it's definitely the method I prefer.  We limit our credit card use to specific purchases.

However, according to what I'm reading, I can only create AppleIDs for my under-13 children (and, by extension, use any of the Family Sharing capabilities with them) if my method of payment is a *credit* card.   The rationale given is that this 'proves I'm adult'...  Is this really the only way to prove I'm an adult?

I could understand this rationale if there were a way to have a credit card ON FILE but not necessarily requiring its use for purchases, possibly, but that isn't the case either.  So much for a great idea, honestly; families with kids under 13 are probably purchase-heavy, but also in the most logical position to want to avoid credit card fees if they can.  This seems like Apple is shortsightedly shooting itself in the foot on a pretty flimsy premise.