Did you read the article? If it were just an assumption and no effort had been put into investigating the reasons for it and if/how those reasons can be addressed you would be right. From the article:
"A new study from Microsoft sheds some light...gender stereotypes, few female role models, peer pressure and a lack of encouragement from parents and teachers largely to blame."
So no assumptions are being made, this has been researched. This discussion is even about some of that research and it turns out girls are being discouraged by factors that are completely addressable.
> we simply ignore fields where women are over represented
Nobody's ignoring anything. My wife is a registered nurse here in the UK and encouraging men to get into nursing is definitely a thing. It turns out that men who do go into nursing have a significantly higher chance of promotion, which you'd hope would encourage them to and is it's own issue. But please, go off on a 'whataboutist' tangent as though the legitimate answer to every uncomfortable problem in the world is 'whatabout' some other problem.