Masturbation more shocking than sex

from Why is masturbation more shocking than sex? by Tracy Clark-Flory

So, why is it that partnered sex was deemed passable while masturbation was not? James Poniewozik makes an excellent point writing for Time:

Maybe it speaks to how desensitized we are by now to two-person sex scenes. Or maybe it says something about the nature of what really shocks people in a depiction of sex. In a self-pleasuring scene, after all, the focus is on the pleasure and not the display of flesh. It’s graphic in a sensual rather than visual way, and that depiction of enjoyment – raw, primal, without attachment to a relationship – is, oddly, more shocking to people than two stylized bodies wrestling in a bed.