People that argue that Tor enables crime do not realise that Tor also enables law enforcement (LE). Anonymity has been a tactic of LE from the beginning. Undercover LE use anonymous looking clothes to blend in with civilians to monitor criminals, police fighting drug cartels in Mexico wear masks to protect themselves and their families, informants require anonymity in order to assist LE with information. But there aren't sites in the onion exchanging this sort of information, you don't see it, which is the way it is designed to be.