At what point did making books harder to read become a sign of literary quality?

Every so often I pick up a literary novel, settle into my favourite chair, turn the first page and immediately find myself playing a game of "who's actually speaking?"

There are no quotation marks. Dialogue drifts into narration. Characters merge together. Paragraphs stretch for pages with barely a full stop to catch your breath.

It isn't long before I'm no longer immersed in the story. Instead, I'm decoding it.