Delany says that fiction in itself is interactive. While reading something, you think of something else and go and pick it up and read a passage. In that sense it is more interactive than interactive fiction since it doesn’t narrow down the paths that the reader can take.
But isn’t this retained in any piece of text, whether it be printed or a hypertext fiction piece. In hypertext, the author gets to add more paths, more ways to fork away, but these exist in a separate layer on top of the already existing interaction of memory and remembrance.