A social problem exceedingly obvious to gender non-conforming individuals is that society has a lot of exaggerated, distorted, and fabricated ideas of what it means to be a man or a woman. Gender stereotypes give people a false sense of how people feel, what their talents are, and what they are capable of doing. Even more, gender roles can dictate what people are supposed to like, want, and do. It's all very structured, and as trendy as it can be at times to defy it, the prevailing attitudes still favor the gender-typed trends. The conclusion we draw, nevertheless, is that this structure is wrong.
Yet saying society gets gender wrong doesn't answer the question we're interested in: what, then, is gender? How does someone know they're male or female (or something else) without having to rely on stereotyped anecdotes? Is this sort of thing on a continuum from one to the other, or might be male and female be different variables on a two-dimensional grid (allowing for someone to be both highly-male and highly-female simultaneously, and likewise low for each simultaneously). Might the idea of an overreaching gender be an illusion, with people simply needs/preferring/feeling male/female-associated characteristics as they believe is appropriate for them? The idea of being one or the other may work well enough if you can be "close enough" to a particular gender in society's eyes, but that attitude may not be satisfying to someone who sees deep flaws in how society handles gender and (like any good academic) wants to find a much stronger model before applying a gender label even to themselves.
Many people are able to declare themselves as genderless, neutral gender, or at least neither male nor female, and neutrois seems to cover those identities. Some people may not feel comfortable firmly declaring such identities, but they're not right with male or female either. As someone who is relatively agnostic about gender, I sort of look to my agnosticism about religion for a sense of what it means. To me, it means one's identity is tied to the other factors in their lives. A agnostic (for religion) typically does not dwell on religious dogma or mysteries because they've regarded them as unconvincing, so they instead look for meaning in life somewhere else. If gender does not confer meaning with a genderless person, they may look at how gender affects life, but it's not the thing that guides their life actions except when society is being a jerk about it (as would a agnostic when it comes to religion). Rather than being a man or a woman or whatnot, the person is being themselves.