I believe you misunderstand. I have no judgements or ideology here. As an anthropologist, my only dog in this fight is to delineate the difference between nature and culture. You are correct that “since the dawn of civilization” (culture) men have agreed to be admonished to sexually select for younger, smaller women. The oldest of sacred writ (culture) has so admonished, giving the rationale that women who may have already had a child with someone else are to be avoided (culture.) In furtherance of this, small-waisted (though not underweight overall) women were also to be privileged in the selection. The current preference for seriously underweight women is much more recent (again, culture, but why?) as women who are chronically malnourished are not good candidates for childbearing and are frequently infertile and/or unable to carry a pregnancy to term (nature.) You are also correct that as a society we have become obese. For example, 74% of adult men are overweight and this spells havoc for androgen, and therefore sperm, production. We do know from the fossil record that sexual dimorphism manifested as a difference in size, that is, men on average a bit larger than women on average did not appear until the very late neolithic so we do know that the male preference for small women has been determined by culture, not nature and that it has produced the result desired by those cultural imperatives. Of course, we are both responding to an article which was purely anecdotal but most likely entirely trustworthy as such.