Ugh, that's like D&D games where they're like, your character has no idea about what a vampire is because folklore doesn't exist in this universe so no one has ever shared a story ever.... even though the party has a bard who sings about things people have heard
Right? We don't need to spend 7 chapters of a 9 chapter story going "Why does this really old, really rich guy only come out at night and talk about not drinking wine!?!?!" When, the fucking cover of the story says "The Vampire Killer 3: The Vampire That Kills"