It's perfectly possible to consider traits to be culturally assigned to the genders and not biologically determined, and still complain about them. Complaining about innate (and therefore unchangeable) biological traits would actually be somewhat useless.

Besides, nobody denies the existence of biological differences. It's pretty obvious that women tend to have breasts and men tend not to. What's being criticised is:

- Misinterpreting culturally-enforced differences as biological and therefore fixed. Hair length, for example, could be misinterpreted as a difference between the sexes if any aliens did a quantitative study without ever noticing the barbers. Job choices could very well be similar, except the process how they are culturally reinforced are less obvious.

- Making decisions affecting individuals based on group differences (biological, culturally, or imagined): Even if women are 2% at picking stocks, using that information only to hire Alice and not Bob will lead to the wrong decision in 45% of cases because the differences between individuals swamp the group averages.