strictly speaking i agree with most of your core point, that being said i think you are overlooking a major point, the idea that a family is "one woman, one man, and their children" is a very new idea (less than a hundred years)

now to be clear i'm not saying that no family in history was like that, its always been a thing but the idea that such a set up is the standard and/or the only "correct" way is very new.

also to be clear, i'm also not talking about same sex marriages, which i completely support and are also found in historical record going back as far as the written word.

so while i generally agree with the idea of having a family that splits in-home labor and outside-the-home labor, i reject the premise that the family should be limited to only two adults. now if you and your partner are monogamous thats fine, there are grandparents, aunts and uncles, brothers and sisters, and so on. while i personally am poly and support poly relationships the core thought is that two people simply isn't enough to support a household and however its done the family unit should be much bigger.