Nah, I'd say it has more to do with MS Office eliminating the need for typists in 1990 and companies replacing the personnel cost with a smaller licensing cost.
I have a secretary. She is an awesome resource that helps my whole team get more done. Typically, they are folks with humanities degrees who don't want to teach. Where I am, they tend to last about 3-4 years, than transition to project management type roles. They excel there, because after a couple of years tracking down stuff.
Women were not able to avail of all the job opportunities they are now, so their labour was cheap. Now they have better job prospects.