The best way to look at it is to regulate what's feasible. Tobacco, marijuana, alcohol and most types of drugs require growth of a plant in order to create. Until there is a way to keep a constant supply of anything we don't have to make ourselves, they should probably be minimal. I'm all for smoking and drinking in moderation, however I feel if its banned or illegal, it wull still happen. If we dedicate specific resources to the growth and cultivation of these recreations, we may be limiting our other supplies intended for survival.