Its just not beneficial for anyone.
The mum is utterly frazzled.
The employer gets half an employee back
Society is conditioned to think that the only practical way to raise a baby is to give up on work/get live in care.
now, to look at it from a "my mum managed, I don't want to undermine the american nuclear family" point of view:
Yes, mums working is an anathema, but given that exceedingly difficult to own a good house, have good health insurance and have an economically inactive partner at home, I suspect the problem here isn't the mum. I suspect its the salami slicing of wages to the average joe/joelle.
Even if it undermines the american nuclear family, having such a big obstacle to the "correct"[1] type of family having babies is going to undermine the "correct" family having babies. Which means one's chosen view of family dies out with inflation.
Given that _every_ other "civilised" country has some sort of rudimentary care for new parents, which doesn't acutally cost that much, I can't see any reasonable objection to not having it.
[1]I'm not going to define what correct is, its divisive and allows people to project what they think is wrong with "the other side" who ever they might be, rather than engage with the specifics at hand.