If the general solution to career advancement is just to work more hours, we'll be a bunch of unhealthy, overworked burnouts.
Where's that expectation that you have to be best of the best coming from?
(Not to mention, the expectation to be seen and treated as the best of the best, without putting in the work.)
Sure you can put more hours into something to get better and improve your performance.
But why should you spent more hours on your free time? Some employers grant a free "afternoon" every-week for employees side projects. Guess what more side projects, less burnout...
Source: The company that support PostgreSQL for my workplace do that. Which we were doing the same.
People are going to have kids regardless. So, the question we're really asking is, should we structure things so that people have time to raise those kids that they are already going to have. I haven't reviewed the literature, but I'd guess kids who have their parents present in their life have better outcomes.