I think what's dangerous frankly is when crypto "experts" try to claim something is when it ain't -- in a public forum.
You just can't make a claim and then say later, "But I'm not an expert."
Whatever. Go forward with your witch hunt. I personally never use crypto myself, though do some contract development on Eth-powered projects.
As about money laundering your opinion is one of a person living in western country with working institutions and strong legal frameworks. Unfortunately this isn't the case in many places around the globe. There is tons of countries where everything is just a question of % you want to pay.
I really can't speak about US and how FBI works, but again most of online criminals are not operate in the US.