People mention that its social lubricant, but I just don't get it. I've had great times with groups that don't drink any alcohol: sometimes we just eat great food, play games, etc. I've had similar experiences with mixed groups of drinkers and nondrinkers.
Interestingly, when I'm in a group where everyone is drinking (except for myself) it seems like the entire interaction has moved to another dimension. Everyone just seems quiet.
---
I guess I should also clarify: when I say benefits, I mean in comparison to other beverages. For example, tea is arguably the healthiest thing you can drink in moderate quantities, short of water [1]. There are obviously more reasons to eat and drink other than health, but for a health minded person, is there any reason to start drinking?
[1] http://healthland.time.com/2012/09/04/13-reasons-to-love-tea...