Most sport, at any serious level, exclude the vast majority of people regardless of gender, gender identity, or biological sex, and sports with a significant sex-associated performance difference offer substantially fewer and poorer paying opportunities for the lower-performing sex whether or not they are sex-segregated.
What does fixed legal gender buy you there?
It means you don't have to deal with as much social and sexual drama between team members for team sports, which I suspect (but don't have data because I don't think adequate studies have been done) distracts from practicing the sport. This is a similar problem to mixed-sex infantry squads. You can wish for all the equality you want, but you won't get it.
It means you have many varieties of sports with women competing that girls and other women can look up to as role models or inspiration or motivation to participate in sports.
There may be a good reason to segregate some sports by some traits linked to sex (but “genitals at birth” probably isn't the best standard for that), but even if there is it doesn't require immutable legal gender to do that.
If the government's standards aren't good, and are in fact simply "genitals at birth", then that needs to be fixed, but as far as I can tell that's not true, at least federally or for the state I checked. If you transition, you get a court document with a doctor's statement certifying it, and you update your gender on your official documents. Right? There probably need to be different legal standards based on the purpose the gender is being used for, too. Being a trans woman shouldn't allow you to compete in women's MMA, for instance; there's already been an instance of that happening and it was a disaster.
What concrete problem or injustice are you trying to correct? That people can't decide to change genders for a day, or decide they want to be officially recognized as the opposite gender before they transition? Is that a problem?
People seem to want [biological] sex labels to mirror how they present themselves to others, instead of mirroring (as closely as possible, based on the reason the gender label is being requested) the underlying sex characteristic / hormonal physical reality of their body. That strikes me as a problem. In the limited situations and cases where people are asking for [biological] gender and need to know, how you present yourself ceases to matter. If they don't need to know, they you can use whatever label you want. Same with your name, or your date of birth, or anything else. But it's almost always pointless to informally declare your gender, because anyone interacting with you is going to pick up on what gender you present yourself as (whether verbally, in temperament, or physically). Labelling yourself other than your biological gender isn't needed for enlightened, tolerant people, and will only antagonize people who aren't comfortable with the whole trans/non-binary thing.
> It gets women in the Olympics.
No, it doesn't. Even to the extent segregation on a fixed biological definition of sex might do that, the IOC can (and does!) regulate standards for that gender segregation (and keeps tweaking details of the rules, which aren't based on fixed-at-birth sex), it isn't constrained to using legal gender as the basis. So fixing legal gender around some biological traits at birth doesn't get you anything in that regard. Which should be obvious, even aside form knowing the Olympic rules, just from the fact that many participating nations (including the current US) don't have immutably fixed-at-birth biologically-based legal gender, and are well represented by women in the Olympics.
That's a complete straw-man argument, no one is arguing for the complete abolition of gender categories. They are there, they are useful, they fit 99% of humans, and 99% of humans can be correctly categorized at birth. It's perfectly fine.
The argument is that legal gender shouldn't be compulsory or immutable.
As for sports, which still doesn't have anything to do with legal gender, it's obvious that trans women could have an unfair advantage over cis women in sports that require strength or reach or bulk, therefore they shouldn't be able to compete professionally as women. And for sports where there isn't any noticeable difference between genders, it's to whatever governing sports association to decide on their own rules, if they want to allow trans women - fine, if they don't - fine. Whatever.
Without mandatory, biologically-informed, legally meaningful gender labels, how can the discrimination provisions of Title IX and employment law be enforced reasonably and fairly? Anyone choosing to identify as the opposite of their biological gender will be discriminated against. How do you determine whether the discrimination was due to their gender identity or due to the fact that someone doesn't want to deal with someone who has gender dysphoria? And if gender ceases to be mostly-immutable and ceases to have stable legal meaning, how do you conduct a legal proceeding accusing someone of discrimination based on gender?
What is it that you hope to accomplish? Are you trying to find ways to reduce discrimination? I think what you're proposing won't do that. Are you trying to allow everyone to "be themselves" and damn the consequences? (We just need to fix society to be compatible with people being themselves, naturally.) Maybe if your goal were clearer...
What you said, doing away with compulsory or immutable gender labelling, would do away with any (government or gov't-regulated, which encompasses quite a lot) attempt to identify anyone as anything, so what I wrote might be an improper generalization, but I can't see how that harms the argument, and calling it a straw-man is quite a stretch.
Discrimination is when you treat someone unfairly for no good reason, or for a bad reason.
Excluding trans women from competing in women sports where being a trans woman carries a significant advantage is not unfair, quite the opposite, it would be unfair for all the cis women who are competing. Therefore it is simply not discrimination.
You are the one insisting that sports organizations somehow must use legal gender as the basis for dividing their teams by gender, that is simply not the case. It's a nice default, but any organization has to be free to do whatever they themselves want.
> And if gender ceases to be mostly-immutable and ceases to have stable legal meaning, how do you conduct a legal proceeding accusing someone of discrimination based on gender?
> What is it that you hope to accomplish?
Gender identity is very important to most people, and if your society has legal genders, people who are legally misgendered will be deeply unhappy. Therefore, these people have to be allowed to change their legal gender, or opt out of having a legal gender altogether, if they feel that's the better option.
Your argument against this is that it would be "messy" from a legal standpoint, but the harsh reality is that nature is simply messy, and we have to be flexible enough to deal with that. If current discrimination laws can't deal with trans or intersex cases, then we should of course update the laws so that they can deal with those cases in a fair manner. I don't know exactly how, but I'm sure we as a society can figure something out.
> What you said, doing away with compulsory or immutable gender labelling, would do away with any (government or gov't-regulated, which encompasses quite a lot) attempt to identify anyone as anything
True, that's not a straw-man, it's a gigantic soaped-up friction-less lubricated slippery slope. In the same way that same-sex marriage didn't lead to people marrying their dogs, getting rid of legal gender won't destroy Women's Volleyball, I promise you.
Gender identification may not be directly relevant to narrow performance in a lot of other areas, but it is relevant to overall human behavior, which affects personal choices that end up affecting things (like work and hobbies) even when performance on specific tasks is not directly affected by gender differences.
Just because corner cases cause problems doesn't imply we should do away with any attempt to identify anyone as anything. Not identifying people according to easily discernible (in the vast majority of cases) characteristics causes its own problems.