> but it would take some time to explain exactly why not...

Not really:

"I'm churning credit cards for the rewards points. Here is the receipts where I use $10k from account A to purchase $10k worth of gift cards. Here is the statements where I deposit $10k of gift cards into account B. Here is the statement for the $10k wire from B to A. And here are the receipts for the next round of gift cards I purchased. Any further questions? I have $10k of gift cards to redeem."