And from a "nuclear family" point of view, most cultural traditionalists I know would argue to me that it's good for kids to be in multiple-parent households. When people talk about stereotypical traditionalist nuclear families, these are very often families that have extended support structures of multiple people involved in child-rearing.
Opponents to parental leave (even feminist opponents) are in some ways attempting to equalize the time-off risk between mothers[0] and fathers. And that can be done by reducing the mother's time off to zero to match the father, but it can also be done by letting fathers get involved in early child-rearing and giving them more time to help their partners.
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[0] And nonbinary/transgender/adoptive/etc parents too of course, but I'm just using a shorthand here.