As a student at one of the biggest party schools in the U.S., I see a bit of a different story from what you’re telling.
Yes, in some ways drug use is going down. I can count on one hand the number of people I know that smoke cigarettes more often than occasionally. However, I know a significant number of people in my generation (there is a slight overlap with cigarette smoking) who vape or use nicotine or tobacco products in some form somewhat regularly.
Beyond that, weed still prevails, and definitely more often than is reported. (I’ll refer to it as getting high to encompass both breathable and digestible versions of the drug.) Some schoolmates will get high at the end of almost every day, either before doing homework to mellow out and focus, or after homework to sleep or hang out with friends. Fewer, but still some, get high at the beginning of the day before even going to class, claiming that they need it to focus and manage their anxiety. (I call BS on that, and I don’t think a lot of them actually believe it, but it happens nonetheless.)
Of course there’s the weekend — the typical party nights are Thursday through Saturday for us here, though some people do so even more — where getting high, drunk, twisted, or attaining any number of states, including rolling and tweaking, is all too common. We may be consuming substances less frequently. However, I’m inclined to argue that when we do, it’s at a much higher intensity than previous generations have.
This may be due to the specific atmosphere of a large, wealthy party school, where access is easy and punishment is minimal. It could be due to the pressure that we face, where it’s no longer an achievement to graduate from college with a 2.7 GPA; rather, it’s almost shameful, in some circles, and certainly to post-graduate jobs and further study.
As one that, while not actively participating in my school’s party culture, has paid witness to its process and impact on students, I have a different theory. Our generation has grown up with more safeguards than previous ones. Yeah, some of us got through high school without getting too drunk or arrested, but the way we were told off from certain life activities — be it drinking, drugs, minor illegal activity, or even eating certain things — most certainly suffocated us. Every generation has been protected from some things or others, but in comparison, we grew up bubble-wrapped and constantly guarded by our parents. Thus, when we get to college, a place where our parents can’t control our every move — though some certainly try — a lot of us let loose and overdo it. We want to try things, we want to experience and live our lives in our own idea of what will make them enjoyable. For a lot of people, that means going on more outdoors adventures and choosing a major that they’re interested in, if they’re lucky to have that agency. For a lot of people, that also means trying all the illegal stuff your parents said would kill you, because it gives you a sense of independence to defy them.
This isn’t to say that it’s a logical response, but can college kids always be expected to act logically? It doesn’t matter if they don’t remember a night, because in some ways the fact that they don’t empowers them even more, because even if it was a bad time, at least the decisions they made were theirs and theirs alone.
Tl;dr: your article hits it on the nose in some ways, but disregards the influence of different environments on substance use, and doesn’t take into account the growing habit of binging when use occurs.