It is a segregationist policy. And it makes it possible for the government to come up with discriminatory policies.
I am familiar with this sort of feminist writing. I am not going to pay 39 euros to see what the exact reasoning in this article is, but I guess it likely argues that registering a child as a particular sex is going to influence how it going to be treated, and that in turn has some effect on how their bodies develop; which may not be entirely wrong but not as big an influence as the article's summary makes it sound (to those not familliar with this sort of feminist writing).
Predictable sweeping (and baying) dismissals from the peanut gallery. Plus ca change.
I take the same line as you, and (like you) I am absolutely not dismissive of the notion that there's some degree of feedback loop between biological sex, physical characteristics, and gender (and gender expectations).
Here is an absolutely true story which I think happens to illustrate the concept quite well:
When I was around 14, an RAF colleague of my father's had a daughter named Nicola who was about a year or so older than me. We kids spent quite a lot of our summer holidays together (the RAF base we were at was at the far end of North Wales), much of it revolving round a lake where we could use canoes and windsurf boards, and swim.
I found out almost immediately that even though I was above-average in things like strength and swimming speed for my age, Nicola could beat me hands down. I soon learned that she was a county-level swimmer, and regularly trained multiple hours per day, in and out of the pool.
Anyway, that summer came and went, and I thought no more of her. And her father was posted to another base over the next winter, so I never saw her again. But about a year later, my mother (who'd kept in touch with the parents, who were my parents' friends) asked me,
a propos of nothing, what I'd thought about Nicola and particularly her body shape. Slightly weirded out by the question, I replied that I'd thought Nicola's body shape was kind of average, but obviously athletic.
My mother then revealed the reason for her question. It turns out that Nicola's school headmistress had contacted her mother, to say that they (the school staff) were trying to turn Nicola away from her swimming and swimming training..... because (and I swear this is the absolute truth) they were worried that Nicola's torso, shoulders and neck were becoming "unladylike" and they were concerned that this might become a more permanent feature of her anatomy and might limit her life chances as a woman.
So yes: I
do think that there's a certain feasibility to the notion of a person's biological sex "label" creating a direct and/or indirect influence upon their physiology and anatomy as they grow up.