Step stuff as step-family porn does nothing for me. Doing your stepmother is basically just banging your dad's new girlfriend, unless she became your stepmother when you were a child. It would piss your dad off, sure, but I can't say that idea makes me hot. Same goes for other step relations, really. I guess people who have step-family members in RL might find the idea hot because it plays into their own fantasies about their not-by-blood relations. People who are into the incest taboo (in porn, that is, hopefully not in real life) generally aren't looking for step porn.
The real reason studios make step porn is because they can't do overt biological-incest porn, which is what most people who are into the niche really want to see, because of our puritanical overlords at the credit card companies and their censorship compliance policies. The step thing is just playing the game.
There are maybe a couple of videos on here that really embrace the taboo, if you skip over the ritual dialogue pointing out that the characters are not really related at the start. Studios making such content are taking the risk that at some point in the future the arbitrary rules will change and the content will have to be removed because it suddenly offends the almighty payment processors or there's been a new moral panic about 'THE SICK FILTH ON THE INTERNET!'. Making sure the step words are always used is safer, so most producers just play it safe.
'Fauxcest' used to be a huge genre in porn. That's why there's so much 2D content out there if you search for it. Plus there's a ton of stuff on the tube sites with 'step' in the title but the content isn't step at all, because clickbait. Only one studio here is dedicated to the genre that I know of and SLR does the occasional video in a series. Then there's VirtualTaboo (not on here, of course) which honestly is super-bland 90% of the time.
Anyway, this rant is increasingly off-topic but despite what OP seems to think, this site isn't drowning in step porn and if you don't want to see it, just mute the one studio that specialises in it and ignore the occasional video from the others.