Have you ever tried to create an event that competes with the structures of other established events? Because it is exhausting and more likely to fail than succeed. People who compete in competition level events have to meter what money they spend to travel and a lot of the rigid rules of competition sport means of you don’t make one event you basically lose your ability to compete.
This whole “uh but it’s your problem to solve” attitude ignores the fact that to run and set up a competitive league you need a lot of people to sacrifice all the time they would be competing and participating to become full time event organizers and just hope against hope that other athletes will potentially sacrifice a portion of their travel funds and squeeze time out of their schedules to participate in a league that will offer no widespread accepted accolades for decades after it’s establishment.
And no, there isn’t that many events where trans people can participate. Even a lot of sports that do not have a sex based advantage have exclusive policies or total bans. Even in the ones that nominally allow trans people to participate there’s catch 22 clauses that place limitations that the organizations know sound inclusive on their face but make it nigh impossible for all but the athletes with extreme mental fortitude and can check a very narrow window of boxes to theoretically participate. Particularly in amateur and community and school related competition spaces oftentimes trans people are just seen as a logistical problem that it’s easier to just create bans for or allow other participants to drive them forcefully out by offering offer no protections against transphobic complaints.
What a lot of the problem is is that trans issues are not very well understood by the cis population at large. It’s very easy to dupe cis people into thinking something that isn’t explicitly a total ban because when you do not understand the actual psychological challenges of being trans you do not really understand when the barriers are solid. Like if you think “oh a trans person being forced to complete in the category of their birth sex until the age of 18” isn’t basically a complete way to eliminate participation of trans people in the sport - then you are missing some key knowledge about the intersection of transition physiology or key psychological and social factors.
A rule like that means first damn near no athlete will have the mental fortitude to make it that far and no scout will ever select them because either an early transition required for them to continue as an adult will eliminate them from competition between the ages of 16-18 or in the case of a masculinizing transition make it seem as though their advantage is unfair driving them to be eliminated via social prejudice.
“Oh just make your own competitions” ignores that sport is regimented as fuck and people who do sport do so at personal cost. People who do sport don’t do so out of the generosity of their own hearts. It just isn’t that easy. It’s literally easier to change the regulations of what pre-exista because otherwise you basically are just in exile from the community of the wider sport.