I've had friends who've died from purchasing bad drugs at raves from people who were looking to make money and run. In one situation it ended up being rat poison. The guy had other drugs in his system, and combined with the poison his body went into shock. With darknet markets and independent lab testing networks, this type of thing doesn't happen.
People are still going to use drugs. I'd rather law enforcement go after the guys who are selling rat poison at raves than the guys who are setting up safe distribution networks.