There’s a loneliness epidemic and low alcohol consumption rates are a contributor to that

Getting drunk and then talking to a bunch of people you don’t know is how people meet people. That’s an essential and long running aspect of human socialization.

If you regularly talk to new people and make friends in other ways then that’s fine. But clearly the majority of Lemmy/Reddit users aren’t doing that. And young people in general aren’t doing it either. Meeting strangers irl and chatting them up is how you make friends and alcohol facilitates that