It doesn't. It's a dumb argument put forward by misogynistic men.

Dracula had sex.

If vampires have no blood in their body, what do you call that stuff they suck out of people's necks and ingest? It's not like they can digest it, they're dead. According to lore, it stays in the body and infuses into their organs. Are testicles not organs?

Also, according to lore, vampires are mystical, meaning they have magical abilities. Are we truly to believe that a creature than can transform itself into a bat is incapable of transforming himself a stuffy if he wanted to? Especially given that vampires are all about wanton lustfulness and sexual energy running amok?

Like I said, this argument from men is clear misogyny. I swear it's the disco ball glittery skin from the movies. It was just too much for men to swallow; they lost their minds. The books described it as a much more subtle effect, specifically it was described to be like granite. Not bedazzled with sparkle sound effects.