There's a practical problem about time and energy, and a more subtle problem of what it does to a writer's head, to continually analyze why they write, where it all comes from, where it's going to.
“I stopped and gazed on the little dull man who was being paid to be a teacher of teachers. I turned and walked to the door, slammed it closed with a bang, and broken glass crashed to the floor. There was uproar behind me in the class, which did not interest me at all.”