If we have more women in STEM then we must have less men in STEM unless we grow the total number of STEM jobs by the same amount.

So those men who would otherwise be in STEM must move to other professions, which means they either move into other male dominated professions and make them even more unbalanced or there must be an equivalent push to move them into a female dominated industry.

If we do the latter then a possible outcome is a system where we are allocating people to jobs based primarily on demographics rather than interest or aptitude.