> "maintain the sharp boy/girl product division"
You're assuming what they're doing is unprofitable and irrational. But a majority of families with two or more children have children of opposite sexes and a cultural taboo against different sexes sharing the same toys means parents need to buy more toys. It isn't hard to believe that this strategy is profitable on net.
So it's really showing the other thing -- not that the market isn't efficient, but that it can be efficient/profitable for the market to be sexist.
But that makes the analogous thing in tech that boys are encouraged to be programmers and girls are encouraged to be nurses. Which is a thing that happens predominantly in schools and at home and it isn't clear how the software industry would be a beneficiary of that -- which is perhaps why we hear many calls to do something about it. The profit-seeking behavior is to change it.