The only reason I continue with that system is because of things like sex-specific diseases, or how diseases affect genders differently. For example, COVID-19. It kills twice as many men as women - killing so many that it’s lowering their life expectancy. In the US, it would be by 2.2 years. [1] However, it’s possible that it’s due to testosterone as that has been found to be the reason for men’s worse immune systems when it comes to being sick. So it’s possible that trans men with the same levels of testosterone fare like biological men and trans women with the same levels of estrogen fare like biological women.
[1] Why Celebrate International Men’s Day? - Men Are Human (Note: I did not find the specific research paper on it, but it should be on an article linked on the website, and then you can find that research paper through that article. However, there is still lots of information about COVID-19 affecting men more on that article and site.)