I don't see why this is hard to understand. If you're spending so much on childcare that it eats up the majority of one parent's salary, that parent might as well stay home. The problem is that it's the usually the woman giving up paid work in favor of being a stay-at-home parent, as if the general assumption is that the man should work and not raise his kids.
It’s worse than that because you don’t get preferred tax treatment for childcare so you have to pay for it in post tax dollars, plus on the low end those post tax dollars disqualify you from government benefits