I smoked cannabis for 20 odd years, most of my friends still do, so I have some experience on this subject. This article ,unfortunately, bears absolutely no resemblance to the reallity of cannabise use. It seems to come from someone who has ingrained misconceptions on the subject, and therefore precludes any objectivity. This is typical of the factually inaccurate reporting of the dangers of drug use, where the writer is of the opinion that it is obligatory to show any drug use in the worst possible light, in order to somehow dissuade young people from partaking of such.
This practice is ,in my opinion, totally counter productive. If a young person in bombarded with messages about the dangers of cannabis use, then subsequently learns from personal experience that it's really quite safe, then he just may assume that the messages warning against those drugs which really are harmful, are equally overblown.
Don't treat people like idiots, give them true and unbiased facts. Let them make their own informed decisions. People have a right to decide their own fate.