Furthermore, using biological sex as the discriminator in sport doesn’t just create unnecessary conflict for intersex and trans players, it also excludes cis-gendered people who are talented, love sport, but just didn’t win the genetic lottery. Dividing leagues by metrics other than gender gives everybody more opportunity to participate. Again, going back to boxing, if the only metric were gender, most or all of the people outside heavyweight class wouldn’t be participating at all.
Finally, I would also argue that team sport is more interesting when greater varieties of people with different strengths and weaknesses can play together. If we designed video games the way we run most sport leagues, matches would be split up into tanks vs tanks, dps vs dps, support vs support. Congratulations, you’ve made things “more even” by separating everyone using superficial physical traits, and lost most of the interesting dynamics of pitting different strengths against different weaknesses.