Anything that enhanced his desire enhanced the value of her goods. If pornography actually stimulated demand, it might even be seen as something which empowers women. More likely, masturbating to pornography simply drains a man of energy he might otherwise expend chasing a mate. The harsh realities of sexual economics may contribute to the discomfort many women feel when viewing pornography. It is cheap sex, and it competes with what she has to offer.
Competition always drives prices down.
Anything that took resources away from the sexual barter system was branded by the system as an unnatural perversion. Of course, these competing sexual sources all failed to offer progeny. Another group of perversions has come along to disrupt traditional sexual economics. Both welfare and the freedom to take jobs make women financially independent. Like pornography and masturbation, these offer competition to the barter system's goods.