Heartiste wrote about the ideas in 'Sex at Dawn' in 'Polyamory is Disguised Polygamy':

A happy hippie free love egalitarian commune it would not be. Widespread polyamorous practice where childrearing is done by the village and all men, uncertain of paternity, contribute resources to the well-being of the single moms and their unholy bastard squirtage, will not convince women to equally distribute their sexual favors among the men. Just the opposite; it would liberate women to single-mindedly pursue the few alphas in their purview, knowing full well that a beta blood-latticed safety net exists to protect them from destitution. In other words, socially-sanctioned and state-supported polyamory lets women have their cake and eat it, too. The only trade-off is that they will have to share scarce high value lovers with other women. Yet as any tour of a college campus will demonstrate, most women in their prime would prefer to share an alpha stud than extract commitment from a beta schlub. Until the wall looms, that is. Heh.

Even if we disregard female mate choice, especially when they are ovulating, the most "baby-friendly" men are out-competed when mating is based on sperm-competition, as they have smaller testes.

Sex at Dawn is essentially a gynocentric fantasy of beta men changing diapers while women take turns riding the alpha. AF/BB in a socially accepted form.