This chart has been floating around, and I find it interesting to speculate about the reason for this shift.
Have attitudes changed this much? Do teens have less independence or fewer places to go to do these things? Are parents more involved in teens’ lives? Was vaping excluded in the study?
My first inclination is always to be suspicious of self-report too, but presumably any biases would also be present in the older data. If anything, I’d guess kids 50 years ago might have felt more social pressure to not admit to alcohol/substance use.
Edit: to your point, I bet you’re right about social media addiction. If most kids are just going home and spending time online, they’re probably not doing these things as much. I bet it’s also the root cause to those studies showing that young people are having less and less sex.
On a positive note there is also less pressure to have sex you are not ready for or just do not want, less virgin-shaming, and more awareness of asexuality and people who fall under that umbrella. By the time I was a high school senior there were plenty of opportunities where I could have had sex but I just did not want it as an asexual person and people actually respected that instead of telling me I’d be lame if I didn’t, or that I had to put out for my partner.