Violence amongst end user drug dealers is very rare and confined to specific, very poor, areas. Wholesale is the only place where you start to see significant amounts of cash, and hence most of the problems, and that has zero differences between offline and on. There is no 'political narcoterrorism' between the guys selling 8ths of coke in the neighborhood. You're also mischaracterizing the drug trade with regards to consumer habits. Drug users communicate about dealers and products the same way people communicate about every other local business. The internet has greatly expanded and enhanced this ability, but prior to the Internet, local businesses, just like local drug dealers, operated by word of mouth and competed in many facets of service. We know this as drug quality has gone up and up over the years.

Remember, the vast majority of offline drug deals do not consist of driving to the hood to pick up something from a gangster. I think this mis-perception clouds a lot of the analysis of operations like the Silk Road.