Why do people get so drunk they can't walk?

Image from passedoutdrunkguy.com.
Yes, there are entire websites devoted to the genre.
I was surprised by this. I shouldn't have been.

Mark Morford on SFGate.com asks a good question:

What the hell is the appeal of severe, excessive drinking, over and over again, to the point of illness and physical collapse and extreme stupidity and brain-melting moronism?

I have never understood the appeal either. The author goes on at great length explaining that he's not talking about getting "buzzed" or even just "drunk", but actually drinking so much you get incapacitated. And he's not talking about people who have an alchohol addiction, either. After trying out a few explanations (generally crappy life, a desperate attempt to connect, sadness and self-loathing), he goes on to say:

Or maybe it's none of those things, and what I see and what you see every weekend in bars and street fairs and house parties across America is merely the way of the culture, just everyday people blowin' off steam in the only legal way they know how, not really knowing when to stop because, for whatever reason, they simply do not have the proper mechanism, or forgot they were supposed to cultivate a mechanism in the first place.

Which is, not at all ironically, the exact problem of our national character, our global identity as a whole. Huh. Go figure.

"or forgot they were supposed to cultivate a mechanism in the first place." Are people really like that? I don't have much contact with heavy drug users of any kind, legal or illegal. So I don't have any particular insight into their functioning. My reaction to stories of this kind of drunkeness are remarkably traditionalist in tone: How vulgar! Don't they know any better? Who brought them up to be like that? They're destroying themselves! I wouldn't want to live in a neighborhood where such people were visible!

Getting drunk as a form of hedonism or as a form of release from social pressure or to lower inhibitions or to engage in a bonding ritual: all these things I can understand. And indeed I have even engaged in one or more of them on occasion. But all those goals are achievable without completely crippling one's mental and physical functioning. What is it that pushes people into that zone of staggering sickness?