You might disagree with this point of view, but that doesn't make it unreasonable.
As Wright notes in https://www.realityslaststand.com/p/sex-is-not-a-spectrum, this view of sex as a binary system is based on the concept of male and female being the two discrete halves of the reproductive system in humans (and other anisogamous species):
"Biological sex [...] is connected to the distinct type of gametes (sex cells) that an organism produces. As a broad concept, males are the sex that produce small gametes (sperm) and females produce large gametes (ova). There are no intermediate gametes, which is why there is no spectrum of sex. Biological sex in humans is a binary system."
Surely this is not an unreasonable starting point for an evolutionary biologist to extrapolate from?
As Wright notes in https://www.realityslaststand.com/p/sex-is-not-a-spectrum, this view of sex as a binary system is based on the concept of male and female being the two discrete halves of the reproductive system in humans (and other anisogamous species):
"Biological sex [...] is connected to the distinct type of gametes (sex cells) that an organism produces. As a broad concept, males are the sex that produce small gametes (sperm) and females produce large gametes (ova). There are no intermediate gametes, which is why there is no spectrum of sex. Biological sex in humans is a binary system."
Surely this is not an unreasonable starting point for an evolutionary biologist to extrapolate from?