This film is not representative of youth as whole
I've seen many posts about the accuracy of this film portraying teenagers, however, this movie is only accurate to represent some groups, but not most of them, let alone all of them.
World wide illegal drug consumption per year is under 5%, which includes pot as well. There are countries where a big portion of the population (up to 40%) has tried pot at least once, but regular consumers are a minority. Other types of drugs are even much more rare.
Sexual promiscuity among teenagers isn't that common either. Teens, specially males, that are promiscuous or have been with more than one woman might be vocal in order to sound cool, but that doesn't mean that they're in the majority.
Sex and drugs might have been part of some people's lives at some point and for some Kids hit close to home, but for many more it was just a reality seen from far.