Earlier quoted context omitted.
I think it's still a form of sexism to assume women are the ones who need to care for a child. They're definitely the only ones who can breastfeed(at any practical rate anyway). One may, of course, elect not to do that, but it does make a difference for the child.
Why is 6 months of time dictating the entirety of childcare?
Children don't magically become independent when they turn 1 either, they need a lot of investment from both parents in order to develop harmoniously.
Starting at this point one could wonder if fathers couldn't spend the same amount of effort as mothers. Technically they could, but by that point they probably aren't very good at some kinds of care and bonding, nor is the baby used to them in that way, unless they already did it during the first year.
It's also not something that is appreciated by others, except maybe the mother, if she can get over their clumsiness and has the patience to teach them what to do. All in all, there's no benefit for the family if the fathers instead of the mothers work part time or stay at hole.