Because cryptocurrencies are not linked with a savings account, so it's not possible to have a service that provides credit based on your crypto coins.

Visa and Mastercards are universally accepted, so their Credit and Debit both types must work on a payment portal.
I recently tried coinsbee.com that offers a maximum of $100 prefilled debit cards.

I haven't seen a "credit" card in the crypto space before. And I see it difficult to see the classical financial banks to accept crypto for their credit cards.