Alcoholics are often better off avoiding alcohol than trying to maintain a light buzz when partying. It's also easier to setup and use safe transpiration before people start drinking.
It takes less willpower to avoid buying soda/chocolate/candy/etc at the supermarket than it does to keep some in the refrigerator but drink it in moderation. It's easier to avoid driving recklessly in a normal car than a sports car. People are more rational when shopping for a car online than in showrooms.
The entire risk in alcoholism is that you won't be able to stop drinking once you start. It isn't a disease where a single glass of wine damages you. Avoiding the wine isn't an irrational act; it's the most sensible form of risk mitigation available.
Examples, please?