It's ridiculous to assert that literary is the most difficult genre to write in. It's the easiest. The world and the people you write about are at your fingertips, at your disposal, everywhere you look; you spend twenty-four hours a day living and breathing them; it frees you to focus on the mysteries of the human heart. Writers of science-fiction and fantasy have to do everything writers of literary fiction do, they just have to re-imagine the entire world as well -- the language, the history, the future, the science and technology, biology. You know, the universe. Those who write in the literary genre get all that pre-packaged for them gratis.
Pick up any three literary magazines at random and give the fiction a read. You will find a few good stories that stick with you, a few that are somewhat memorable even if you don't like them as a whole, and a lot that sound as if they were written by the same person: the narrator is a self-afflicted, self-obsessed loser drifting aimlessly through awkward, ugly, and annoying encounters narrated in flat, listless prose that reflects the flat, listless lives in which they are trapped. The other end of the spectrum is the hyper-observant story whose every detail is a mildly offensive grope at profundity. I've read those stories a thousand times, and they never get any better in the retelling. And it demonstrates that 'literary' is very much a genre of fiction: if re-using the same character types, the same narrative techniques, and the same faux-artistic description isn't 'genre', then I'd like to know what is.
Silly article by man with silly name.