If you look at the etymology of the word gender you can see that the original meaning of the word is class.
The purpose of gender is to create artificial divisions between people in order to maintain an artificial hierarchy, and prevent the most competent people from assuming the leadership position.
In the past there were two genders: man and woman. A divisions based on biological sex.
Sex is not the same as gender, sex is determined by your natural biology that you are born with, there are male, female and the rare case of hermafrodit.
However gender is different from sex because, gender comes with a prescribed artificial behavior.
For example if you are a man you are expected to behave in a certain way otherwise you are not going to be considered a real man. There are natural predominant patterns of behavior for males, determined by things like hormones and other biological factors.
But man are expected to behave in certain ways that are not necessarily dictated by biology or even the best interest of that individual. For example: real man die for their country, real man don't cry, or the way a hysterical woman night tell you that you are not a real man whenever you are doing something that displeases her. Generally speaking being a real man means to sacrifice yourself for others at no benefit for yourself.
The word man comes from Old English man, mann "human being, person (male or female); brave man, hero; servant, vassal,".
Not to far ago woman were locked in a certain position by their gender classification. This restrictions were purely artificial, there is no reason why woman couldn't pursue higher education, careers or become athletes.
By simply classifying woman as unable to pursue this paths you eliminate them out of the competition. Simply the fact that there are now woman successfully pursuing careers it proves that the restrictions were based solely on social convention's not facts. Sure there are some not so desirable negative side effects, like the changes in the family or the increase competition in the job market etc.
Besides that what defines a man is neither empheric or objective, what defines a man changes all the time arbitrarily.
Being considered a real man in the eighteen century is almost completely different from what most people would recognize today as the ideal of a real man.
Gender is a straw man argument, a man is a fictional title, whit arbitrarily defined characteristics and patterns of behavior, as well as artificial negative consequences whenever the individual deviates from the predetermined behavior.
It is impossible to have genders without authority, and because of that there are no free man. Free man is really a pleonasm as a man is a servant, sa then saying free man you are really saying free slaves.
You could make the argument that a lot of the tools we use are based on fiction. Like money for example, there is no real value in a bill but we all pretend that is it valuable because it allows us to better compare the value of goods and exchange it, there are a few negative side effects like inflation, but the benefits exceed the negatives.
Gender on the other hand is fictional too but the benefits of it I can't find, it doesn't make people be better parents, kind or fair. It does quite the opposite, it allows people to exploit and abuse each other.
The current debates about feminism or gender pronouns, are great in some ways, but both sides are missing the main point. One side is so identify with the fictitious title that they are resisting any changes, while the other side are simply trying to redefine what gender means. That is like arguing over what super power elf's should have. But the reality might just be that there are no genders and we don't need it in order to function or accomplish anything.