No one denies the 2 sexes. Gender is the issue. Most people conflate the two, I'm not saying you are. Even the people advocating for change conflate them because society for so long equated the two. Sex is assigned, by people or god or the environment or random fate. Gender is completely created and defined by society and that's where people actually want change to happen. I get what you are saying, but the fight for gender fluidity is a worthy fight - it's hard to see past the confusion, but I honestly believe no one thinks there isn't genetic differences based on sex, even if they sound like they don't.