About six or seven years ago I was a member of a US-based professional website of writers, which had thousands of members (still has but it's less active since most members migrated to Facebook). I was a member there almost since the inception of forum discussions, so I watched the gradual escalation of how writing about violent sex went mainstream.
I remember well how members over there over time began to chat about SM as if it was the most ordinary thing in the world. Female members. How they liked it. They would deride people who liked "vanilla". How they wrote about it, how they were angry at Amazon for censoring their work.
A couple of the female writers wrote extreme porn. You were not allowed (on pain of being called judgemental and outdated) to criticise or say you thought porn was awful, as it meant you were judging another person's livelihood.
I remember one of the authors researching the world of incels for a book. She eventually wrote it. She was very anti-incel and everyone was horrified at the things she said about that world.
This person is the most rabidly pro-trans person I've ever had contact with. I am still 'friends' with her on FB but have blocked her from seeing my posts.
The violent sex these people talked about at the time was very vague --no graphic descriptions of what went on, (which I would not have read anyway). I never read their actual books. They liked to mock books like Fifty Shades (which I haven't read) because it was all so "amateur" and the characters in those books weren't doing it right.
And those were only books, forming pictures in one's head. With videos, actual living porn actors and actresses, acting out the scenes, how much worse.
Without having read the books, I do think the Fifty Shades phenomenon played a part in normalising something that most women, I think, would find repellent. Since then people, women, seem to be more accepting of SM as normal, healthy sex. It absolutely is not. I think that liking violent sex points to mental disturbance. But it's not something you can say out loud these days.