This is crap. Only thing true is adolescent use is not good.
Getting high comes at a cost. How you want to assess that cost is up to the individual, but it also affects society in lost production and reduced initiative. Given that teens are the heaviest users, that cost can have long term effects that are not trivial. Both sides of the debate are propagandists, so the middle ground is hard to find. Personally, I believe that the WOD has caused more damage to our country than pot use, but unfortunately, I don't see legalization significantly affecting the cancerous growth of Federal powers.
Sorry to burst the Libertarian pipe dream, but the more likely result will be drugging the masses into more insidious state dependence as has been shown in the European programs...