Amphetamines makes you write a lot, but in the end it's not good writing, you just end up rambling way more than neccessary to get to the point. One of the perks of good writing is being able to successfully transmit the message and emotion while being as concise as possible. That's why Anton Chekhov is considered by many the best short-story writer ever. He's writing is incredibly simple at appearance, extremely succinct and somehow it's perfect, it sounds like it'd be an easy style to emulate, but it takes a lot of discipline and talent to be able to say so much with as few words as possible.
Yes Amphetamines gives the FOCUS and MOTIVATION to write.
Small doses of Ketamine gives me creativity like no other thing, much better than harder psychdelics, because Ketamine being only slightly psychedelical it keeps the writing very creative and original and at a level that anyone can follow, writing on LSD gets a little too Thomas-Pynchon-level-confusing minus Thomas Pynchon exquisite writing.
The thing is, I CAN'T write on K alone. I just look at the screen, or paper, and never start a sentence, but when I combine with amphetamine, I get in the zone and start writing, the anesthetic effects of Ketamine seems to give me discipline, I don't ramble, I actually care about every sentence, and they all pop in my mind with ease, I think the slight dissociation makes it so we can more easily think of new ideas, original ideas, that are not so attached to our persona. That doesn't work with LSD, because LSD is simply magnifying all your thoughts and believes at the same time, but in the end it's still all you.
I only believe in The Death of the Author argument if I know the author was writing under dissociatives, or just boderline psychotic, that works too.