There's an immense gulf between how Japanese is spoken, and how it's written.
While I'm not going to go write a thesis on it, it often feels like each major literary revolution in Japan has been accompanied by a group of writers who have taken their writing one step closer to the colloquial speech they and their peers use.
Haruki Murakami owes the bulk of his success to this; his writing cut through the calcified formalism of Noble Prize winning pretense with stories that evaded literary importance by not really being about fucking anything in particular, written in a jazzy conversational tone that felt and still feels like a breath of fresh air to anyone who's struggled through a recognized literary masterpiece. (Not to knock those masterpieces unduly; some of them are genuinely worth the slog.)
But Murakami is an old man. He's my parents' age. He stays relevant, but there is a generation gap there, and he doesn't sound like people my age talk.
Light novels are more colloquial, yeah, but often with an artificial anime filter; the gap between anime voice acting and actual acting, if you will.
It often felt like the writers in Faust were the only people writing in modern voices, in the language as it was lived and used. There may have been others, but I never found them, and these guys banded together and put out a magazine that effectively is the voice of their generation. It may lack the literary pretensions of two generations ago, and it may not have the polite disdain to be about nothing at all, but to these writers, genre writing feels more relevant.
Full House probably didn't turn every Japanese man into a pedophile the way Nisioisin claims, but he's also admitted Eva single handedly ruined him for life, and there are probably a dozen other writers and manga artists who bear equal responsibility. He's a writer who reaches through truth by exaggerating it, the magnifying glass of his ornate writing style, bizarre plots, and deranged characters letting him capture something about the collective imagination of his generation that is fucking important. The instinctive grasp of character nuance in Kadono Kouhei's character-study-as-action-horror body of work; the incisive way Otsu Ichi reaches out and places his finger right on an emotional tremor; Tatsuhiko Takimoto's desperate attempts to keep himself from going insane on page; and Maijo Otaro, sadly left out of Faust 2, whose single-minded pursuit of reckless rage-fueled surrealism makes him a literary movement in himself...
Each approaches their work in a different fashion, each reads and feeds off the others voices, and without them, Japanese literature would be dead in the water.