There's no fundamental property of the monetary system that prevents transfers of arbitrary value across international borders. There's just a large number of financial regulators, border guards, etc. who will throw you in jail if you carry a big block of gold across the border or accept a large wire transfer without filling out the necessary forms. In many countries, the laws governing those forms don't yet apply to cryptocurrencies, but I'm skeptical it will remain that way forever.
That's true, and the AML laws for crypto are already becoming more strict, especially in Europe. But in practice, it will be much easier to evade those laws than it is with fiat transfers or moving physical cash/gold.
But you’re reinventing money with extra steps.