On Writing - Drugs v.s. Creativity

Some of the greatest literary works in history are supposed to have been written or conceived while the author was high. This naturally leads one to make the association that more drugs equals more creativity. A reasonable associaton while reading Alice in Wonderland for the first time, or Fear and Loathing in Las Vegas. However, it is questionable as to whether this is actually the case.
Stephen King says in his book On Writing, that "the idea that creative endeavor and mind-altering substances are entwined is one of the greast pop-intellectual myths of our time." For King, this is not a topic for debate. He is stating that that link is myth. It does not exist. And he should know. He spent years as an alcoholic and sniffing cocaine, worrying about whether he could continue the way he was. After a while, he just stopped caring.
In his book, King also describes not being able to remember writing his book Cujo. If you can't remember writing something, did you actually write it? If it's a question of bad memory, then yes, you likely did write it, unless you plagiarized. However, if you can't remember because you were so hopped up on drugs at the time, it's debatable whether or not you actually wrote it, or whether it was the drugs kicking your brain into overdrive and spewing words out at a hundred miles an hour.
There are many fantastic books written by sober people, or people who were sober when they wrote them, at least. Often, authors who partake in drugs and alcohol are more well known for their questionable habits than their literary works, which is a great pity.