It's more like... if 1 good female developer gets a CS degree for every 10 good male developers, you would expect the workforce to be 10% female. However, if you artificially force 50% female representation you'll have to start drawing upon bad female developers since the rate of good developers is currently only 10%. You first have to increase the output of good female developers from schools before you can scale up their representation in the workforce, not the other way around.