21 points
Because the author plays with the physical formatting of the book, and physically having the copy you’re reading is important for getting the intended experience. It doesn’t work right with an ebook
I remember some rumour that an early version was web/hypertext based, which would’ve been interesting to experience.
I still have very little evidence that anyone other than hypertext narrative writers and English Lit grad students actually read (traverse) hypertext narratives these days, though.