On top of what everyone else said about the forbidden fruit being that much sweeter, it's much more prudent to teach kids to respect alcohol and its effects in more controlled settings. How many college freshman who have never had a sip of alcohol before get in all sorts of trouble when they go to that first party? They don't know what to expect, they don't know their limits, they don't know moderation.
When you teach a child to swim, do you just toss em in the Atlantic and see what happens when they say they want to go in the water? No, you let them wade in their swimmies and play splashy splashy, and then hold their nose underwater, and then floating and strokes, etc.