Alcohol on its own does not cause social occasions or reduce loneliness. Plenty of people drink alone, and plenty of people gather socially without drinking.

That said, while the advice from a health standpoint is that no amount of alcohol is completely safe to drink, humans do risky shit all the time for fun or convenience. More people get hurt in car accidents than develop alcohol-related diseases, but no one is stopping driving. The difference in outcomes between people who have zero drinks per day versus 1-2 drinks per day is much less than the difference between 1-2 and 5+ drinks. So occasional/light drinking is still relatively low-risk. It's just not actively good for you as previously thought.