It's because the experience of so many parents these days is exhaustion. There just aren't enough hours in the day. In my experience it often turns out that if

It's because the experience of so many parents these days is exhaustion. There just aren't enough hours in the day. In my experience it often turns out that if a fellow parent has significantly more personal time than me (for side projects, exercise, whatever) it turns out there is an unequal distribution of labor in the household. For example, a spouse who doesn't work who handles all the domestic stuff could allow the other spouse more free time. That same stay-at-home-spouse could find themselves with a lot of free time as the kids get older and require less hands-on parenting. That sort of thing.