If you're not careful your shop can become a drinking fraternity first, dev team second. What happens when someone who does not drink wants to join the team ? Well just the fact that he doesn't drink can make the rest of the team feel like they're having less fun and that they "can't have as much fun drinking now" so they might (subconsciously) decide that the highly qualified non-drinker is not a cultural fit. That's fine in an environment where new qualified recruits are easy to come by.. but is that the world we live in ?