I've mentioned on a couple of occasions that if you want to win a Nobel Prize in literature it is essential (1) that you not be a white male American, and (2) that you not use quotation marks. The first is due to a statement by one of the judges that Americans are too focused on themselves (they've obviously never read or met any writers at all). The second, I thought, was mere stylish pretention. Not so! I have figured out why writers do this, and for a good writer how it enhances their reputation.
Imagine reading a slooooooow book. Slow as in, you're on page 200 and nothing has happened. The writer is being very stylish, but there are no events that might be charitably called a plot. If the main character wants something, he or she is making no effort to achieve that goal. And you start to skim...
We all do it. Glancing at the description and reading the dialogue. This turns the novel into a screenplay and lets us skip ahead to the page where something actually happens. Because certainly some character will say "Oh, my God!" or equivalent and then we can drop back into the story and figure out what's going on now that something is.
Now think of reading a novel with no quotation marks and no offset dialogue. How do you skim? You can't. You have to actually read all the words. The author has told you that every word is important. And you have to read every word. Further, they are subtly telling you that they are important, because every word is processed through them. They are not in the business of simply reporting what characters say. The writer becomes the conduit through which everything flows. The story is not the point. The writer is the point.
In a slow-moving book this technique just enhances the annoyance because the reader is trapped. In a good book, well, good luck with the Nobel committee.