There is no compelling evidence they are 'rampant money laundering machines'. Even to prove money laundering happened, you have to prove a crime happened that generated illicit revenue that was then laundered, in which case prosecuting for the AML violation would be redundant, as the offender could be successfully prosecuted on the root crime.
This is why AML laws make much more than money laundering illegal, why in the vast majority of cases of AML law violation, no money laundering was proven to have taken place, and why none of the analyses on the volume of money laundering use this burden of proof when formulating their estimates on the scale of the phenomenon.
What you could say is that other venues are less compliant with warrantless surveillance requirements of US financial crime regulators. That is the phenomenon that is actually provably rampant in non-US-regulated crypto exchanges.