Nah, it's an increasingly common thing. Participation in a specific subculture can skew your perception of reality, especially if your fellow subculturists are the only human beings you interact with on a daily basis.
>why would something even more alienating be a viable concept?
It can work if there is a large enough customer base in a specific area, which is why almost all weird fetish clubs are based in a metropolitan area. As I mentioned earlier, there was a preg bar in Tokyo or something, but that only worked because is guaranteed to be at least a few tens of thousands of ninpu fetishists within train distance. Even given Japan's suitability for the weird, a lot of these physical locations are being squeezed out by fetish meetup sites like Fetlife and dating apps that let you search for people that fit your bill.
Abe-san (RIP) had the chance to normalize pregnancy eroticism and missed his chance.