Saying that an eighteen year old isn't emotionally ready to
drink alchohol is ridiculous.
The truth of the matter is that you've delayed their experience of alchohol for so long that by the time they get to learn how to deal with it, the mistakes they inevitably make - at 21, 25, or 38 - are crippling.
At 11, 14, 16, 17, and even 18, that's not so much a problem. A drunk kid is much easier to deal with than a drunk adult, and an adult who was a drunk kid at some point is far less likely to want to become a drunk adult - because they know what happens if they don't moderate.
Understanding succeeds knowledge when faced with curiousity. A kid who feels how much fire stings, won't jump into it as an adult. A kid who's told that "fire burns", might just be curious enough to want to learn what it's like as an adult.
Or to put it simply, your claim is the
opposite of true.