1. In many cultures it's not kosher for girls to complete with boys. Mostly a young boy v young girl thing
2. Having been a chess coach for 7 years I can attest that mindset lives here as well. Many girls prior to abt 13yo and under don't want to deal with boys, or as little as possible.
#2 can be discussed at great length, but I'll pass. My name is not Sigmund Freud and I'm just a lowly retired Industrial Engineer, not a psychologist.
ETA
Some / many of the powers that be in chess come from a culture that isn't Trans centric. They're less likely to be swayed by that "movement "