People shouldn't be able to buy crypto on credit for the same reason we cannot purchase lottery tickets, and Stocks on credit. If someone wants to buy Crypto on a loan, they can simply get a cash advance, and purchase their Crypto from their bank via debit. If your bank won't let you make purchases of Crypto via debit, get a new bank, and let them know why you are leaving.
RE: Another Bank shuts down buying Bitcoin with Credit Cards