Hey, we have a long-standing rule not to mod while under the influence!
Granted, moderating does make me really, really want a drink now and again. 
As for the topic, the system as proposed by the OP is superfluous at best, and a costly waste of resources for no measurable gain at worst. Alcohol abuse is a problem, and one that is already largely addressed by existing taxes and ID laws. As others have already said, if you want to combat the problem further, you need to instigate societal change. Right now, there is a very pervasive notion that alcohol consumption (sometimes to excess) is pretty much required for certain social activities to be "fun." Parties without booze are looked down on compared to those with lots of alcohol available, clubs and such have arbitrary rules about the number of drinks you have to agree to buy in order to get through the door. Movies and television often play up these tropes, along with playing drunkenness for laughs. Much like tobacco use was portrayed as the "in" and social elite thing, so long as alcohol is socially held up as required for fitting in or socializing, people will fall into the trap of overdoing it/getting addicted. Change the media portrayal, and you'll see a much bigger decrease in usage, again, much like tobacco. Couple that with better education and access to addiction treatment, and you'll tackle the problem far more effectively than merely duplicating the existing licensing and ID system for selling/buying the stuff.
