I don’t know that I agree with that. Otherwise rapists would force someone to mow the lawn and things like that too.
It’s about sex.
Saying rape is not about sex is like saying bank robbery isn’t about money.
There are horribly obvious exceptions out on the ends of the bell curve, but that’s in the main.
Not saying the rapist doesn’t enjoy the sex side of it but regular sex doesn’t give them the thrill that the humiliation, degradation that rape gives.