they couldn't afford to have kids because they couldn't subsist on one income.
I am sure they can subsist on one income, it's just that they don't want to.
I don't think that distinction matters much to the point Azathoth123 is making. (Personally I'd put the family in that thread in the grey area between "couldn't subsist on one income" and "maybe could but it would be terrible". Husband and wife on $10k/year each. I wouldn't want to try supporting a family of three on $10k/year, though maybe it could be done if "supporting" means "living on the streets and barely managing to feed" or "scraping by using every bit of government-supplied assistance available".)
I remember seeing a talk of the concept of privilege show up in the discussion thread on contrarian views.
Some discussion got started from "Feminism is a good thing. Privilege is real."
This is an article that presents some of those ideas in a way that might be approachable for LW.
http://curt-rice.com/quotas-microaggression-and-meritocracy/
One of the ideas I take out of this is that these issues can be examined as the result of unconscious cognitive bias. IE sexism isn't the result of any conscious thought, but can be the result as a failure mode where we don't rationality correctly in these social situations.
Of course a broad view of these issues exist, and many people have different ways of looking at these issues, but I think it would be good to focus on the case presented in this article rather than your other associations.