The interesting thing to note here is that just because a categorization is useful doesn't mean it's something that concretely exists. To buttress what GA was saying, even biological sex is a social construct to some extent.
I'll quote from this article and skip straight to the most relevant point of conversation, but the whole piece is pretty informative reading.
https://www.autostraddle.com/its-ti...cal-sex-to-defend-their-transmisogyny-240284/
The test I use to see if is a social construct or not:
1. Would it have existed without society?
2. If we were to roll back time, could it have been constructed differently?
Money is a social construct, because it's contingent on the existence of society; it does not have any value without it. If we were to roll back time, we could have decided that toilet paper was the currency if we wanted.
Now, biological sex. Our evolution into a sexually dimorphic species does not depend on existence of society. Whether the concept of 'sex' is created or not, the mechanism by which we propagate, which is the fusion of two distinct gametes from opposite sexes, will continue to manifest regardless.
Could it have been constructed differently?
Maybe a slight variant, but it's even hard to imagine. Here, we have two categories with a set of insanely correlated traits: the combination of gametes x gonads x hormones x reproductive organs x physical anatomy x secondary sexual characteristics happens to hold true for about 99% of humans. Is this just some meaningless category that we decided to place them in? I don't think so.
Also, the existence of intersex people does not disprove anything. Biology is riddled with errors, and unless your claim is that everything is a social construct (even the fundamental laws of physics were different before the big bang), I don't think its fair to say biological sex is.
I don't think anyone intends to argue that the labels male and female aren't useful, but where your presentation, in my opinion, begins to falter is when you implied that sex is something immutable and concrete whereas gender is not. It's a phenomena that needs to be taken seriously. It's hard to know to what extent gender is influenced by biology or culture, mostly one or the other, or somewhere in the middle. Simply because we don't know absolutely everything about something yet doesn't mean it should be written off.
lemoncatpower said it was primitive, but whatever. FYI I don't think gender is a social construct either.
I have reasons to believe it's mostly biological (see the experiment of
David Reimer). For a little extra detail, Reimer committed suicide at age 38.
I can see how someone could have questions or confusion about gender within the parameters I just mentioned but I don't understand why it's being framed by some people as some sort of politically correct fad that other genders might exist other than man and woman. It's dismissive and ignorant of the conversation that's actually being had.
Edit:
I forgot to ask. If, by what you said, something being useful is the prerequisite in order to be deserving of existence, or at the least categorization, why isn't recognizing multiple genders useful?
I have no problem with genders that are not male or female. It becomes a 'politically correct fad' when people try to say biological sex is a social construct to suit their agenda.
However, I do have a problem with people thinking that gender = personality, and that if you don't like to play football and drink beer you must be non-binary. Dysphoria is a real condition, so I don't like the people who claim to be genders that 'change depending on the weather' or something. That's bollocks.