Look at the work/life balance of your typical engineer in the tech industry. Compare this to the reality of a mother of small children. In our culture, women disproportionately bear the brunt of child rearing.
When there's a work emergency and the kids HAVE to be picked up at daycare, who goes? When a kid is sick, who stays home? When a child is born, who takes several months of leave to care for them?
Consider that many women leave the tech industry or stay away from the all-consuming work culture because they have or will eventually want a family life. It doesn't matter what are people's abilities when they see a job as incompatible and contrary to their life goals.