I'm wondering if it's helpful to identify these as 'sexualities'? Might it be a bit limiting for people to say 'No, I only get attracted to people in this form?'
How are they more helpful than all the “traditional sexualities” though?
Someone at one point decided that præferences in gender should be treated differently than other præferences, probably because it was birthed from trying to use the good old psychiatry, an everlasting ally to enforcing political morality, as a means to classify some præferences as “wrong” by saying that it was an illness — so they reclaimed the illness and it was then called a “sexual orientation” and we're left with the situation that “præferences in gender” are to be treated differently from other præferences with no real scientific reason to believe that they are fundamentally different.
I suppose now other præferences want in on that too. I don't necessarily consider it different and they may do as they will, as they aren't hurting anyone with it.
At the end of the day, there is no actual scientific standard for “sexual orientations”, and it's but taken as self-report, and, attempt one to devise one
viā measuring symptoms of arousal, it becomes considerably more complicated — in that sense it's not that different from “race".
Had we lived in a world where psychiatrists had attempted to create medical diagnoses out of the then-sin of feeling attraction to a different race than one's own, we would have probably ended up “sexual orientations” related to race now as well.
If no-one really fits into the gender binary then how it is so ubitiquous?
I see a lot of people at the moment, especially men, dismissing the gender binary as all about stereotypes and thinking it doesn't really apply to them because they don't like football or sometimes cry when they're watching a film when in fact this represents a tiny part of what gender is and the social power it has.
A lot of gender, how we speak, our body language etc is unconsciously performed we learn it so well. Gender is how we dress, and how we present ourselves, and this indicates our social role and status in the gendered hierarchy immediately to others. I suspect one reason men are much more rigid in their physical gender presentation than women is that typically masculine presentation indicates a superior role, and most men don't want to give that up. Gender is even how we choose to make ourselves smell if you use that kind of stuff, although in reality this is chosen for us, and it's interesting that deoderants and products for men often very obviously specify themselves as being FOR MEN in a way women's don't, because men won't buy them if there's any ambiguity.
Gender is the job we do, and how much we get paid for it. Gender is whether someone expresses, or possesses a sense of internalised male privilege due to their gendered socialisation even if they are not consciously aware of it. Gender is whether we are worried about walking the streets late at night or getting in an Uber driven by a man on our own. Gender is how much reproductive work we do (in the Marxist not biological sense) such as care work or emotional labour. I'd even argue gender is linked to sexuality as in the perfectly gendered male, with all the social rewards that come with that, would be pretty much exclusively top and heterosexual. And yes, gender is about tastes, and interests, and coerced personality types, but all of those things are supported and maintained by the deeper elements of gender, and the fact that gender is not just something we consciously choose to perform but something that happens to us, whether we like it or not.
But it doesn't completely fit for most. All those things you mention will rarely be 100% one way or the other for any given singular human being.
For men in particular to shrug off the gender binary as just being about some stereotypes that they don't think apply to them then is really just a way of abrogating responsibility for the way gender benefits them. And most of the men who do it in reality are near perfectly gendered males in the context of a modern neoliberal and patriarchal society that doesn't really need men swaggering around and starting fist fights every five minutes.
But they're not in many ways; they will always have many things in their lives, their professions, their mannerisms, their hobbies that will be considered “feminine” and such considerations are quite arbitrary.
I can't say I care, however. I don't see the merit in compulsively “gendering” random social behavior. It isn't worth more than trying to compulsively assign it labels like “western” or “eastern" and wonder whether one's profession or behavior isn't particularly “eastern”.
I think it's probably true that some teenagers who are non binary are really just rejecting gender stereotypes based on their physical sex, although it's equally true that many non binary people feel a sense of disassociation with their physical bodies in the way many binary trans people do. But I also see a lot more non binary people really interregating the core of gender and exploring alternatives, including things like presentation which is a big part of gender, as well as social structures which enforce gender, then I do those men who just decide the gender binary doesn't really apply to them, and then carry on being just as gendered as before without any social cost or real reflection.
For what it's worth, there was a research in the Netherlands that investigated this and concluded that both in cases of “incongruent gender identity” and “ambivalent gender identity” about 1/3 had “gender dysphoria”.
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If you wish to read it, you'll have to do so through
Google Translate, but the numbers whereof I spoke are on page 4.
It should be noted, however, as something that is often overlooked, is that the majority of transgender persons does not meet the medical criteria for “gender dysphoria”, which is why gender identity incongruence absent gender dysphoria was declassified as a mental illness — the mental concern is gender dysphoria which is similarly a mental illness that depression is; if one have feelings of gender incongruence but this otherwise not compromise one's life, it is not considered a medical concern.
....... that's as much to do with my age as anything else, but still!! 
