Comparisons between humanity's ten million year old association with alcohol and drugs are false on the face of it. Alcohol was completely ingrained in the culture, and it could not have been banned by passing a law.
Libertarians are always trying to say drugs are exactly like alcohol. They are trying to take a case with a specific and thoroughly engrained substance, and to assert that banning all other substances is exactly the same.
No, it is not. Drugs never met the percentages of usage and popularity that alcohol has always had. Drugs have been successfully kept down to level of 2% of the population which was the same as it was a hundred years ago when they first banned them.
Past-month pot use is 7.5% - and past-year is 12.6%.