I see.
Problem is it's one thing to be dark, but something else when your writing isn't just bad but outright irredeemable. Nasu's writing isn't just terrible it's pure trisomy 21 if the backstories of Mordred or Jack the Ripper weren't a hint, not to mention the abomination that is Fate/Zero. Nasu himself, or the fans might say how this is allegedly deeper than you think, but the reality is it's just Nasu writing embarrassingly terrible fap stories about his waifu, his degenerate fetishes and in some cases even pedophilia. Minus the letter, it's a similar situation with Druckmann whose terribly written fetish game is hailed as something deep and dark.
Not only does the comparison with Neil Cuckmann stand, Nasu manages to be even worse.
Credit where credit is due however, I do enjoy the memes that came out of this godforsaken franchise, especially the Astolfo ones. And Gilgamesh is the only good character.