Having the declarative knowledge then being able to practice it. I am sure most people know that they are supposed to eat 'healthy'. It can only be one part of a larger program to combat obesity.
If we extend this to alcohol, then we should ban all alcohol. Alcohol is generally fine in moderation or occasional use. But if we need to ban things because a minority of the population misuses it, then we will have an extremely long list (butter, sausage, steak, etc).
Then you need to increase your reading comprehension. I nowhere said or implied "ban".
Or you need to examine your biases; are you perchance a libertarian? Or really right-leaning in any way. If you're American, chances are very good the answer is 'yes'.