Can I get an American credit card only with a tourist visa?
It should be impossible. Maybe you can't even get a debit card, which is a domestic debit card. Because banks don't open accounts for you, many American banks require at least proof of address to prove that you are a permanent resident of this place. The requirements for credit cards are even higher. They used tourist visas to open credit cards, and after spending, they returned to China, and the bank could not receive the money. They can't be unaware of this risk.