Isn't gender based on stereotypes? What's wrong with getting rid of stereotypes?
No, gender isn't based off stereotypes. Gender roles are. Gender is in part based off the concepts of masculinity and femininity, a dynamic sociological concept that does not apply rigidly across sex. When you try and uniformly apply those concepts based on dangly bits, then it becomes stereotypical and often prejudicial.
Just like nationality, another sociological concept, has undisputed common cultural traits but attempting to uniformly apply to all people under one national label is unhelpful.
If anything, broadening our understanding of diversity under identity labels, not dispensing with labels, brings more utility.
Now, in a premiere utopia society might it be nice to not have things like nationality, currency, spirituality, gender, etc? Some people certainly think so, but regardless we don't live in that reality and so we shouldn't pretend those things don't exist with relative positive and negative connotations they bring.
And, like I said, this isn't about eliminating complexities OR stereotypes. It's about eliminating trans and nonbinary identities. Let's be fr.