Those who disliked the fact that the reason behind the spiral was never explained missed the reason for why it was never explained and the power it had. As soon as you understand the motive or process of what it is you fear, it becomes less terrifying. By not telling us how it came about or who built it, we're left feeling just as terrified of the spiral pattern after finishing the novel, which is what the author wanted and it's much more effective, in my opinion. It just goes to show how much people, especially in the West, have been affected by the Three Act Structure storytelling and how most people in the West rely so much on it for story narratives. There is no reason that the Three Act Structure needs to be followed and, in my mind, often times the stories that are able to deviate from this often have a much greater affect on the audience and are able to get across the intended effect of their story.
