@mentrix It's a less common interest presumably, it's probably fair to say there's a stigma about it, and I believe it's even a hidden category on the site by default. There are probably not nearly as many performers willing to participate as they will in other porn. It might also be hard to market, and mainstream studios might not want to be associated with it. Whether it's a substantial risk or not, in the USA it's also a particular type of porn that has apparently resulted in prosecution and jail time. https://www.vice.com/en/article/why-is-the-guy-who-made-2-girls-one-cup-going-to-jail/
I'm don't know what the legal status is in other countries.