culture.

There was a NSFW territory at the beginning of the territory explosion, but it died off. I suspect it's because most people don't come to SN looking for adult content and there are a number of stackers who actively dislike it.

Also, SN is primarily a text-based place: it isn't really optimized for images or video. So I imagine the creators who are looking to make money via adult content but who are also willing to limit it to text are few and far between.