If you were to waltz on down to Germany you would see many a human drinking at age 16. Is that okay? I'm not sure it is, but let's be honest, most folks have had a drink by 16, if not a lot of drinks. It's the old prohibition logic. If you say "Don't drink when you're 17", then people will naturally listen, right? No, not really. Laws only do so much, education is the key. You can't just tell kids not to drink, you have to show them why they shouldn't drink, and it can be done, as it has been done with bullying and smoking.
Binge drinking is bad, but telling people not to binge drink at a young age won't stop a lot of people.
People this age are sent to places like Iraq and the like without the proper support of a government that's sent them. They don't get enough ammo, not enough equipment, and there are not enough programs for the ones that come back permanently damaged. These kids are 18 years and up. Why should they not be considered adults, with all of the benefits bestowed upon so called adults? At 21, kids are considered adult enough to legally be kicked out on their own; why shouldn't they be allowed to drink booze and beer? Taking drinking privileges away from 18 year olds may or may not have been a mistake but at 21, being considered an adult and having all of the responsibilities of being an adult it would be a mistake.
Drinking as people now is not to bad when taken in moderation isn't to bad, having a few glasses of wine with a partner is great as is having a few drinks out with some friends. People who just don't like alcohol are entitled to their opinion & don't have to drink, I like to drink & have some friends who don't like it, they are entitled to their opinion.
In Germany, fourteen year olds can drink in the presence of a legal guardian, and the drink more than in the US and the UK, yet have less liver disease. All evidence suggests that the earlier a person starts drinking, the more moderate and healthy they are in later life. If you introduce alcohol to a person at 21, they would feel a rush at the sensation of intoxication, and have a higher chance of binge drinking or alcoholism. It is fundamentally better to instill a sense of moderation early on, rather than abstinence and temperance, which will be more than compensated for in later life.
If they can help it. Alcohol is toxic to our livers, and especially as our brains are affected by way of the chemical slowing our neural transmissions, as a depressant/sedative. Especially as at age 21 the brain is still developing, in terms of neural pathways which is the phenomenon that we experience as "learning". Especially since so many alcoholic beverages are addictive.
More recent research has discovered that drinking before the age of 25 will have a negative effect of brain development. Our brains are not fully developed until the age of 25, any drinking at this time can stop the final developmental processes from happening. This includes failing to develop the nesessary inhibitive skills.