Your factors are real, but I think both elements are at play. I admit I could be biased as I see gen Z as more disciplined, locked in, from gyms to lifestyle.

Socialisation, or lack thereof, is a great problem for many people and newer generations raised "online", when you get for free at home endless social media distraction.

But even the 20 year olds I've met in bars were likely to stop drinking way sooner than us milenials, which still get plastered, at least on special occasions.