that isn't true. Kraken is happy to take XMR and exchange it for USD on their fiat offramps for all Americans. They are absolutely not happy to take CoinJoins, and will quickly close your account for doing so. Because Monero is fungible like cash with similarly limited transaction history, which is compatible with American AML frameworks, but CoinJoins are an overt act of money laundering, which they have to psychotically suppress to keep their licenses.