Women and men are raised differently. Things that come natural to you, having been raised male, do not come naturally to a large number of women. Examples include how to make eye contact in an interview and how to shake hands properly. It is very common for women to be raised with an attitude of quietly waiting to be noticed, rather than pointing out their good traits and skills. This can leave them a bit lost when it comes to an interview, which is essentially the time to brag.
Aside from childbirth itself, women are far more likely to be single parents than men are, and are normally the ones to stay home with sick children, especially when there is a long-term disease involved.
Many women end up dealing with multiple name changes, across degrees and sometimes projects.
Of course not all women lack these skills, we would never pretend that to be the case. But the ones that do are at a distinct disadvantage, and there are more of them out there than you realize.
Who would you turn to if you didn't even know that your handshake felt like a dead fish and you never once made eye contact with the hiring manager? That kind of feedback doesn't exist after interviews.