This has been happening quietly for a long time. It exploded now because it crept into new segments like Steam. That is mostly driven by a few conservative groups applying pressure to credit card processors.
You won't find porn sites with certain content; in particular, blood or scat play. Now, neither one is to my personal liking, but I don't think it should be blocked as long as everyone involved consents. You might find amateur videos of it, but never anything from a professional studio. That is quite simply because credit card processors forbid it.
(My source is one of the interviews that Kink.com does before a scene, which they always leave in the edit they post to their pay site. I'd have to search a lot to find the specific one. Suffice it to say that one of the models mentioned "no scat" as a hard limit, and the director said that their payment processor wouldn't allow it, anyway.)
It's also impossible to remake the old Taboo series as is. Faux-incest scenes go out of their way to mention they're all a step family (seriously, how many step children does Cory Chase have? This doesn't seem physically possible.) This is all credit card industry pressure, as well, and while I wish the genre wasn't as prevalent as it is, the setup dialog gets really silly and contorted because of this restriction.