No, we should not do away with the drinking age. The human brain does not fully develop until a person is in their twenties Relying on teenagers to make sound, healthy decisions about alcohol is naive at best, and dangerous at worst. A child does not need alcohol, and they should not be permitted unfettered access to it.
You're either an adult or you are not. If brain development is a concern as another poster brings up we should raise the military age to 23 as well, because combat injuries can seriously harm brain development. What about the fact that it is THEIR brain, not yours. If a person at 18 is old enough to decide who to vote for, whether or not to risk things like lung cancer and emphysema through smoking, and old enough to take many risks including possible death or injury including injury to brain development by joining the military then they are old enough to make the adult decision to drink and old enough to choose to put their brain development at risk if that is what they want. It is their brain development, not the government's brain development.
The prefrontal cortex in humans does not stop developing until we are 23. Alcohol consumption mainly affects this region of the brain. It's important from a developmental standpoint that our children and teens are not drinking at young ages. Alcohol is always something that should be used only in moderation, not to excess.
The age restrictions on alcohol should not be eradicated. It would be possible to lower them to the age of 18 as they are in Canada but to get rid of them altogether would be unwise. Teenagers should not be allowed to drink as much as they want, wherever and whenever they want. Teenagers brains are still developing and as a result they often make stupid decisions and these decisions could lead to car accidents, fights, or alcohol poisoning.