Heres an alternative thesis for you - the monster archetypes in western literature (and of other societies too for that matter) going back many centuries have common elements correlated very strongly with dominant and infernal crime powers at the time. Vampires much more so than any other exemplar.

Its as though conventional warnings would either wane over time or fail to be heeded entirely, so those crafting the warnings had to reach into the allegorical to convey the point - stories and folklore being a timeless thing.