I suspect there's a perception duality going on here wrt the porn consumer.
On the one hand, they're getting off on the fact that what they are viewing is not being mocked up for the camera, it is real penetration/pain/humiliation/male climaxing etc.
But at the same time, they are viewing the acts through the medium of camera/screen, which distances them from the action. Also, the participants, especially the women, are often caricatures of more "normal"-looking women and are performing actions that are far more extreme than most people would have experienced themselves.
So reality and fantasy are both being catered to at the same time.
And yes, I know from personal experience that the porn consumer will then be inclined to try and experience some of those scenarios in real life. Assuming that many women are reluctant to go along with these, it can really taint a relationship.
Suddenly sex loses its intimacy and becomes a vehicle for the porn-consumer to attempt to insert himself into those fantasy scenarios. And most of those scenarios are the polar opposite of loving sexual intimacy.
Personally, I felt less like myself with one particular XP and more like a sex object, a fuck toy.
And that's definitely demeaning.