Here's an interesting WSJ article about the importance of social & emotional connections, and the correlation to career success. As a fan of AMC's Mad Men (thanks SHolmes), this article seems to support the Mad Men way, i.e. drinking heavily for career growth.
It seems like a method from a different age, especially if you believe the buzz about social networking taking over the world. But, there is a long history (going back before written records) of alcohol at the center of social scene. So there's gotta be something to it. And the madison avenue men, if you take Mad Men as historical evidence, certainly made an art form of it.
To me though the point is that making real emotional connections in professional circles is essential, though this article may over-stress the the drink to make the point. Relationships matter. You don't know when you'll need them, so that means investing yourself in connecting. In some cases it may be at the bar. The drink may or may not make a difference, it's just something convenient to huddle around as a group. Now pour me that single malt Islay.