I try to elaborate why I think that the article has some valid points.
This is not about abolishing the categories male and female but instead to look at them in a different way. Instead of the old binary male/female, you're either 100% male or 100% female, you can also see male and female as opposite poles on a scale (see above). This depiction of sex allows us to better understand the human body. Up to a certain point all human fetuses develop the same but then they start to develop different sexual characteristics, not only the genitals but bone structure, muscle structure and probably even brain structure develop differently, this development is not completed until the end of puberty.
To see sex as this scale allows us to better understand and depict problems such as "why did this man not develop this typical male characteristic?", "what influence certain hormones have on our development", "what happens in puberty?", etc..
Another example is intersexuality, intersexuality is not a third sex or something like that, it means that the body was not able to develop enough towards one side of the scale.