Vampires aren't real in general, this is like saying that someone's reimagination of fictional creatures is somehow "less real" than yours, because it is not horror. Well, the horror genre didn't invent vamps. As fictional creatures they exist in different folklores, and with more variety. It is not always evil undead, that is just the trope Western authors like to repeat.
I'm pretty sure there's not a whole lot of folkore vampires that are actually nice people that are just misunderstood, and who really want to fit in, but they just can't fit in, but they really want to be friends, but they can't be friends, because they are trapped in the prison of pure torment that is their lack of a soul!!!
And obviously something can be true to a concept or less true. We all have ideas of what "dragon" means, be it the Oriental or the Western version, so imagine if someone decided to make a story where a dragon was a winged cow that has a very nasty swooping attack where it farts gas while belting "MOOOOOOOOH!" at a terrifying volume? Fun encounter, sure, but what does it have to do with the concept of dragons? Not a thing.
Astarion (and Twilight) have as much to do with the general concept of vampires as a farting winged cow has with dragons. And frankly it doesn't matter if you could find a funny folk tale somewhere that lets vampires be something other than monsters, because that doesn't change the general concept of vampires.
