The average human brain fully develops by at least the age of 21 and sometimes 25 or more, meaning you could damage brain cells if you are drinking before that age. Allowing your brain to successfully develop is an important part of growing as a human.
From personal experiences, people aged 15-16 are excited to get their first licence when given the oppertunity. Meaning, they would already have been able to dive for around 3 years. You are legally allowed to drink at age 18 so you should already understand the responsibilty of driving.
There shoudn't be an limitation for drinking at all. People do what they want for. Whan can be done is only prohibiting what causes directly harm to others. Drinking by itself don't cause damage to anyone but himself, and this damage is not even considerable in a short time spam.