This behavior was also common on the generation which was born during the revolution, like my brother. There was more information on the end of the 80s and teens were still trying soft drugs but starting to avoid hard drugs. I can't really explain why this happened but I know bad stories about drugs were all the time on the news. For instance, in my house my father always said: "If you ever try drugs don't ever come back." He never knew about my brother but there was a cousin in the family completely addicted, he died recently.
I'm on my twenties so I'd say I'm from the generation after my brother's. I never tried drugs but all my friends did, no exception. They just aren't addicted, don't know why. It's pretty common for them to carry small dosages of marijuana which are allowed by law but there's one thing they don't know: it's legal, like the article states. It has to be a really small dosage but it's enough for you if you're not addicted. And that's what's funny: I never met anyone who knew it was legal (and I knew it because my brother worked at the courtyard) and everyone still looks at Amsterdam like the holy place for drugs in Europe. It's like a taboo, nobody is supposed to talk about it being legal, and it works I guess.