Grammar is how an idea is communicated. If a person has an identity they want to share then the pronouns they use communicate their identity, but if they use an uncommonly used pronoun then their identity is not understood, not communicated, and if gender neutral pronouns are used then no identity is communicated, or it's just completely confusing as is the case with using xer. I'm fine with people inventing identities outside of the binary, I'm fine with cultures having outliers to the natural occurring roles the constraints of reality offer, because all cultures and languages developed in different environments with different forces pushing and pulling. What bothers me is the white washing of the binary male/female him/her in an attempt to represent everyone when people invent their own identities which did not occur naturally as a consequence of environment. If a culture has some instances where definite articles are sometimes out of what is naturally expected from the basic grammar then that's cool, but it's still not the norm. You mention because they are exceptions not because they are everywhere.

>, evidenced by how the ideas of “masculine” and “feminine” vary between and even within societies

I did say that they did vary in an earlier comment, but they still follow the biological binary. They are a product of biology. I'm talking from experience of being around different cultures and I have never been in one where men are not generally male and women are not generally female. The same gender roles also still exist, because the dimorphic nature of humans make different behaviors more advantageous for each sex to do.

I'm aware of things like XYY syndrome, but expression wise they are still male.

>third gender

Transpeople exist, yeah! Like in an earlier comment I also said that there is a third option in English the it, but transpeople don't like that word as far as I know because it has a history of being derogatory as is illustrated in the wikipedia page as people being seen as without gender. They are people with gender dysphoria, because they generally would have rather been born the other gender. For whatever reason, as they developed their hormones were not at the male/female ideals and so they expressed in different ways outside of the male/female ideal ranges, and their behavior expressed in ways not common within their natural sex, so they become outcasts being not really attractive or useful to either natural sex in traditional societies. I empathize with their suffering, but I still see it for what it is. There is no plethora of varying genders divorced from sex. There is a lot of made up stuff though with no basis in science. "Social science" isn't.

In English we do have a grammar with gender, and I know that there are generally assumptions about gender/sex which people want to change, and many I do not agree with. How far away is that from real human suffering? How serious should we really take a person who looks like a male within our culture and is offended with a person calls this person a him?

>It is such a different concept than classifying nouns.

Why reply at all to my original post then when the person I was replying to was talking about pronouns, and I was clearly using the word gender defined as an attribute of sex.

If you can make the world a better place with less human suffering then good luck. I see it all as being biologically informed and so useless to even bother with. This dialog is useless too. You've not given me any new information and I already have reflected on it all and I see it as another way. It's not worth either of our time to continue, so, good day to you, xer.