I disagree, there can be social norms and roles that are not related to sexual differences but gender roles and norms do so the distinction can be useful. That doesn't mean that they are also not affected in a cultural way.
Sure, gender-based social norms would be what you are referring to. Maybe we need a word for "gender-based social norms", but that word certainly is not "gender". The word "gender" itself does not mean "a collection of socially-constructed norms that can be changed", which is the modern take. I think "gender role" could be a fine term, as in, "a social role partially or fully determined by a person's biological sex". If gender simply means "socially-determined role for an individual that can be changed", then "gender role" is nonsensical and redundant.
The crux is that biological sex informs the social norms, not the other way around. Altering the word "gender" to infer that society is imposing arbitrary rules upon males and females is a recent lie. It's all language play. Language play is fun in poetry and in music, but it has no place in something as important as a person's psyche. Ego formation is difficult enough as it is.
Gender -- and it's root, genus -- refers to classification based on rigid observable forms. In the context of language, it refers to word conjugation and it is
fixed. "du" in French is masculine and "de la" is feminine, easily distinguished by the form.
In the context of biology, genus is a specific classification for a creature. Gender is narrower, referring to that creatures role in the reproductive process.
Neither of those are fluid. Heck, doesn't the term "genderfluid" itself imply there is a
fixed quality to "gender" that is less-solid for the so-called genderfluid person? If gender itself is fluid, then the term genderfluid is redundant, just like "gender role".
You can blame puritanical normies for this one. "Gender" really only gained use as a term for "sex" when "sex" was narrowed to its definition as copulation. Since "sex" could refer to fucking or to whether the creature was male or female, "gender" entered the mix to eliminate blushed cheeks and confusion.
"Gender dysphoria" is another interesting piece of this discussion, aside from the fact that a lot of people appear to be suffering from it. The DSM defines it as:
Gender dysphoria is a condition where a person experiences discomfort or distress because there's a mismatch between their biological sex and gender identity. It's sometimes known as gender incongruence. Biological sex is assigned at birth, depending on the appearance of the genitals.
This is interesting to me for two reasons. The first is the phrase "Biological sex is assigned at birth, depending on the appearance of the genitals". Please show me other scientific determinations done in such a wishy-washy way. If a biological male is born in the woods and no one is around to observe his genitals and assign him a sex (note how this nonsense is even infecting the term "sex"?), is he a male? The notion is absurd but that is how far the conversation has devolved.
The second interesting part is the acknowledgement of a disorder characterized by an incongruence between someone's sex and their gender identity. Yet, if gender is
socially-imposed, this is not a
medical condition but a
social one. Otherwise, this indicates there really is a natural connection between "sex" and "gender" (using the modern definitions) that
cannot be changed.
None of this information is hidden. Etymology is one of the most well-documented fields of study in the Western hemisphere.
What's most remarkable to me is we condemn the phenomenon of language corruption and language replacement when it comes to
colonialism, don't we? Bastardizing the local populace's language for the purpose of absorption and subjugation has occurred throughout history. We condemn the phenomenon of language appropriation when it comes to race relations, don't we? White folks still can't say the n-word in polite company, for instance.
Yet, academia is engaged in the same bastardization and appropriation when it comes to biological terms. I can only assume ignorance or duplicitousness.