The shift may be less about fundamentally new content and more about explicit labeling and marketing of elements that were previously present but implied -- i.e. -- SEO.
SEO contributes for sure, but I would reverse the statement here - it's more about new content and less about SEO. There's a feedback loop race to the bottom dynamic regardless
So I'm actually kind of lost here. As I understand it, your theory is that the anticipation of SESTA/FOSTA caused there to be more professional porn and less amateur porn on Pornhub, which in turn caused a "race to the bottom" in porn titles, along both rough/violent/rapey lines and incest lines at the same time, and furthermore that the titles reflected the actual content?
So you believe SESTA/FOSTA led to an unintended increase in the actual violence you'd see if you watched random videos on Pornhub?
I don't think much of SESTA/FOSTA, but I do think that's kind of a stretch.