Abso-freaking-lutely! Reading anything, imho, contributes to helping you write. You can’t write without being a good reader. That’s one of my pieces of advice to new writers: read, read, read. Reading will expose you to different sorts of writing styles and all sorts of information. Read fanfic, read newspaper articles, read biology texts, read published literature, read poetry, read novels. Read trash. Read smut. Enjoy yourself. Revel in the power of words; what they sound like when they’re conveying information. The somberness of an obituary. What sentences make your gut clench or your heart beat faster. The phrases that make you sigh. The combination of dirtiness and vulgarity that turns you on.
But I can’t tell you how many amazing fic authors have inspired me in my writing. There are fanfiction authors out there whose writing is so beautiful that I will read anything they write, regardless of the fandom. Authors who really know their craft. Fic authors exposed me to the different ways a story could be told. The beauty of fanfiction is the democratization of literature. That is: anybody can publish. Anybody can be an author. So you get a huge variety of voices. Think about those five times, five kisses, five things type stories. What an interesting format for fiction! Or I love those character-driven pieces that focus in on one character -especially side characters – and telling their POV, illuminating them in a way that we would never get in canon. Stories that explore villains and their motivations. Alternate Universes that take the characters we love and transport them to an entirely different setting and how the author translates that. Dirty smutfic written with real lust and desire (and I’ll read any fandom if a fic has my kinks in it).
Fanfiction teaches you that writing can be anything. There’s no limits. It’s so beautiful, man.