Right, in terms of greater society it fell away for a reason. However on individual levels it has far more going for it beyond just sex like polyandry does. You can actually sell its benefits to both genders without having to overcome biological instincts, as women's jealousy is far less of a dominant force.

Point being not that it is a goal to work towards, but that it is a better step out of monogamy if that was their goal. And that in avoiding it entirely, betrays their actual goals.