I'm of a mind with @Animedragon. I think it's nice if two potential partners happen to share common interests, but speaking from my personal experience, having things in common does not necessarily equal being compatible. My ex and I had a ton of shared interests, and things were great between us for the first few months of that relationship. But, the more we learned about each other personally, the more different we discovered we were from each other, and the more miserable we both became in it. Our core values didn't align at all, and none of those common interests made one bit of difference in the end. So, I'll reiterate Mr. Dragon's point about being cautious about seeking out such relationships based solely on interests.
As for creating an anime-centric dating site... I suspect the results of that would be about the same as it would be on the usual go-to apps (Hinge, Tinder, Bumble, etc.). You might (keyword: might) get lucky if you live in or near a major city, but for most folks like myself that live out in the sticks and have to drive well over an hour away to get to said cities, the pickings tend to be quite slim.