You can't understand the difference between making something illegal that has been legal and legalizing something that is illegal?
When an act that has been illegal is legalized, the amount of the activity increases.
And, alcohol usage did drop during prohibition:
http://www.sarnia.com/GROUPS/ANTIDRUG/argument/myths.html
Prohibition was a solitary effort by this country while the rest of the world was essentially "wet." However, most drugs are illegal throughout much of the world. This makes enforcement much easier. History shows that prohibition curbed alcohol abuse. Alcohol use declined by 30 to 50 percent; deaths from cirrhosis of the liver fell from 29.5 per 100,000 in 1911 to 10.7 in 1929; and admissions to state mental hospitals for alcohol psychosis fell from 10.1 per 100,000 in 1919 to 4.7 in 1928.[53] Mark Moore, Harvard professor of criminal justice, wrote: "The real lesson of prohibition is that society can, indeed, make a dent in the consumption of drugs through laws."[54]
People like the guy writing this article simply can't bring themselves to admit the similarity between outlawing MJ and outlawing booze. Bootleggers made booze in the states also until it was legalized and then the vast majority of them went out of business and organized crime got out of the booze business and if MJ is legalized the Mexican pot growers will gradually die out. They don't want to become visible to the government, therefore they won't become legit. They will look for other illegal activities such as smuggling in cocaine or other drugs.
The fact is medical MJ has already eaten into the pushers business in CA.
You don’t remember the Kennedy’s?