I think you’re a little confused about what it is they were asking. They weren’t asking if wanting to not have sex was a fetish thing, they were asking if seeking out partners specifically who have never had sex is a fetish thing.
It’s not the same thing as wanting to date an asexual, because not all asexuals are virgins (often due to experimentation and discovering “yup, I don’t like this.”) The reason so many people want to date virgins specifically is because they have this weird idea that taking somebody’s virginity is a sacred thing. Or sometimes it’s just due to insecurity, not wanting to have other past partners to be compared to.
Wanting to date a virgin isn’t wanting to date somebody and not have sex with them, it’s wanting to date somebody who’s never had sex before. Whether they will have sex or not during the course of that relationship is technically irrelevant, but most people seeking out virgins specifically unfortunately are expecting it.