Hey, now. I consider myself somewhat of a writer and I have no difficulty whatsoever staying sober. it's a chicken-egg problem: are you a drunk because you write? Or are you a writer because you're a drunk? Yeah - there's a long line of addicts and alcoholics that have contributed greatly to the world's literature. But there's plenty of people with zero substance abuse problems who have done the same. I mine my pits without any augmentation whatsoever. In fact, I've found that the quickest way to annihilate my productivity is imbibing.
That makes two of us. The only real alcohol I ever had was when I was six, once, under my mother's supervision (she wanted me to try whatever is called "медовуха"). The stereotype of a true artist, however, is against us when it comes to public image. The fact that some of the most popular artists have included various degrees of "high" into their lives (Stephen King and George Carlin are just two names off the top of my head) just adds to that. Apparently, getting high can be a good way either to defend yourself against or attempt to outrun your demons - or the abyss.