It's true that crypto is commonly used in online drug transactions, but there are other justifiable uses, such as moving money out of countries with repressive regimes like China and Russia.

Also paying for certain genres of porn that major credit card banks like Visa and MasterCard have somewhat arbitrarily designated as unacceptable, such as certain types of BDSM e.g. consensual nonconsensual, anything that shows blood, kinky hypnosis and mind control, vampires, etc.

Of course obvious child porn and bestiality should be banned period, so some regulation is needed. But I'm not sure that the government delegating responsibility for regulation to the credit card banks is the best way to do it. The rules and enforcement are completely arbitrary and cannot be appealed.