Isn't 50 Shades Of Grey Rape Culture?

For some reason a lot of the people who frequently speak out against '' rape culture '', also happen to be big fans of 50 Shades Of Grey.

I'm just wondering but.....isn't that literally rape culture? Don't get me wrong, I'm not shaming people for whatever they're into. But BDSM is the direct simulation of rape itself. Tying someone up, whipping them, etc. It's fine because both parties are consenting to it. But where do you think it comes from? It comes from what conventionally constitutes rape.

But totally fine with the feminists lol. They don't mind that kind of stuff being exposed to young minds. It's sexual expression :P