The existence of a marketplace does not constitute the existence of criminal activity, or vice versa. Rather than focus on the monetary transaction, I believe we should focus on the crime itself.
Pushing the monetary transactions for criminal behavior toward the public consciousness is, IMHO, beneficial to law enforcement, even if there is no clear or reasonable way to prevent or even track the monetary transactions themselves. So long as people are educated about criminal behavior, we can have a culture where law enforcement is actually effective; after all, real crime happens away from keyboard.
Pushing the monetary transactions for criminal behavior toward the public consciousness is, IMHO, beneficial to law enforcement, even if there is no clear or reasonable way to prevent or even track the monetary transactions themselves. So long as people are educated about criminal behavior, we can have a culture where law enforcement is actually effective; after all, real crime happens away from keyboard.