If someone who doesn't have sexual experience shouldn't write smut, maybe people who have killed another person shouldn't write about murder.
Maybe straight girls shouldn't write slash.
Maybe people who have never been pregnant shouldn't write about pregnancy.
Maybe people who haven't died shouldn't write about death.
Maybe people who haven't been raped shouldn't write non-con.
Maybe people who haven't lived through historical periods shouldn't write about them.
Maybe people who haven't been married shouldn't write about marriage.

And no one should write anything about magic, ever.

There goes most fic ever written...