Don't know if it's been said before, but in the US the only real reason the Weed is Illegal and Alcohol isn't is that Hemp is a much more flexible substance.
Seriously, in the 30's a billionaire named William Randolph Hearst sank a large amount of his money into Wood Pulp Paper, then discovered that Hemp-based Paper was just as durable, just as flexible, and cost about a third of what Wood Pulp did to process. So he called some buddies in the Senate.
Really, that's the only reason Weed is Illegal while Beer isn't.
(And in WRH's defense, he was also the one of the strongest anti-Nazi businessmen in America at the time- and the first to have the balls to show what exactly was happening to people during the Holocaust in the newspapers he owned.)
(Does it count as Godwin's Law when it's against your own position?)