That’s what peasants eventually do to end a growing drug trade regardless of form of government. It can be done with or without order.
The Chinese have been growing and using opium since the Tang Dynasty 1300 years ago. It was only under Communism that the government started massacring people for growing, using or selling it. One thing I'll agree with you on, though. The only way to eradicate drug usage is mass murder. Countries in East Asia that have limited themselves to killing drug dealers have only managed to reduce drug sales.