What it all comes down to is liquid punctuation. The drinking isn't the occasion itself, just a handy excuse. It doesn't form the backbone, but can cap it off beautifully like a drinkable full stop. It can add a moment of drama in the form of a raised glass, help us pause for a moment and take stock.
Alcohol does funny things to us. This is essentially why we drink it. Many of these effects are positive; that said it is also unfortunately responsible for some near biblical lapses of judgment. This is because deep down inside all of us, in a place we don't like to talk about... there be monsters!