It cuts down on time off because you can work with a hangover. Employees tell management what they think, not what they want to hear. It encourages carpooling. Increases job satisfaction because if you have a bad job, you don't care. It makes fellow employees look better.
Bosses are more likely to hand out raises when they're wasted.
Suddenly, farting during a meeting isn't so embarrassing. No one will remember your strip act at the Christmas party. It makes the new guy feel like one of the team.