The problem changes when we realize that, as with Indian drunkenness (shared with other populations, hence "Irish disease", which I've had in my own family as such because it's true), there are people for whom some substances are too powerful and too powerfully addictive, who lose their humanity because they indulge.
Don't tell me a junkie's going to turn down a smoking heroin joint. Give him a whiff of that, and then impress me by showing me how he waves it off and says "no".
Addiction is a game-changer. It's no longer a matter of free consumption.
Addiction changes the game less if the habit holder is held responsible for what he or she does “under the influence.”