Sure, Look at who put out that link- it's done by a pro-MJ group. The link also uses the words "no substantial increase" so even they admit there will be some increase in MJ use but it won't be substantial, and what they define as being "substantial" is anybodys guess. When alcohol became legal again in the 1930's there was an increase in it's use, even though people used alcohol while it was illegal, it stands to reason MJ would be the same way. None the less your going to have people driving cars with altered brains from MJ use or driving a fork lift at work mellowed out from MJ - thinking he's even a better fork lift driver because he's so mellow. MJ's only real use is to alter your brain, that's the only reason people use it. If MJ had no effect no one would use it.
Quoting people like;
National Academy of Science
Contemporary Drug Problems (yeah, I know - says Federal on it so kiss of death to you...reality for everyone else.)
Bureau of Tobacco Control and Biometrics, Health and Welfare (blame Canada!!)
California State Office of Narcotics and Drug Abuse
British Journal of Psychiatry
Netherlands Ministry of Health, Welfare and Sport (where freedom and liberty actually began...)
Australian Journal of Public Health
If you are concerned about the definition of the word 'substantial', then look it up. And read some of those papers to see what THEY define as 'substantial'.
As for alcohol, the usage dropped according to 'studies' (referenced here if you really want to know what you are talking about...so, I bet you won't look at any of them), mostly due to lower cirrhosis rates by about 10 - 20%. One was confused....
http://en.wikipedia.org/wiki/Alcohol_during_and_after_prohibitionBut YOU know better than all those high-falutin' intellectuals, don't ya...?
For the VAST majority - beyond any "first time" novelty use, alcohol AND marijuana - of people who use are gonna keep using. And the ones that don't, won't.