There's more to this than meets the eye.

It depends on how you perceive writing. For example, "Old Man and the Sea" might be the greatest essay about criticism ever written, despite the fact that it's not an essay. You have to see through the story to get to the essay.

I think the reason so many people enjoy Paul Graham's writing is not only due to the subject or the genre, it's that he transcends the category, much like Hemingway did when he wrote "Old Man and the Sea."

For others who might be curious about the Hemmingway connection, http://petersencj14.blog.com/2013/02/15/an-essay/ seems to explain what you're referring to