Its sexism all the way down - Sandberg would not have done that to a male subordinate (who's wife was giving birth) and a male boss would not have done that to Wynn-Williams.
Women should not discriminate against women in the workplace because they are women.
I'm not sure whether men are truly better on average, or women are just on average more conditioned by our societies not to do so or even if, to do so in a manner that isn't effective.
Unlearning ~2 decades of upbringing, education, expectations, some of that from religion, etc when entering the workforce could be pretty hard and significantly affect any statistics around this.
Women should not discriminate against women in the workplace because they are women.