Working to achieve a 1:1 sex ratio between men and women creates a sense of division by fundamentally looking at men and women as different when they should be looked at as the same in the workplace. It fosters a sense of "otherness", polarization, two separate groups and a sense of difference, when there should be a sense of LACK of importance of gender/sex.
Same pattern applies to racial diversity. By looking at skin color and purposefully categorizing people and trying to achieve a certain balance, you enhance a sense of group-identity and otherness that creates racial division in the first place.
I think this is why this issue seems so intractable. Just by talking about and labeling groups you help reinforce and create those groups and divisions between them.