The use of a neopronoun in a sentence generally implies the following:
- The referent is comfortable with being assumed to be non-binary.
- The speaker is aware of the referent’s gender variance.
- The speaker wants to call attention to the referent’s gender variance in front of the listener.
- Nothing is stopping the speaker from calling attention to the referent being gender variant.
These four basic implications can have any number of variable deeper implications about the speaker, listener, referent, and the context of the discourse, and the relations between these. There are naturally exceptions, too, but I think we can set those aside for now.
We can for instance imagine a situation in which either the listener or a passerby is secretly questioning sy gender or is in the closet, and wants to know who’s “safe” or who thon can talk to about sy troubles. With just a single use of “xe” in a conversation — assuming the speaker isn’t using a mocking tone — we can practically guarantee that the speaker is safe, that the speaker knows someone who’s worth talking to, and that the listener and any passersby at the very least don’t flip out and insist that the speaker should “stop using that word”.
Can you do this reliably with he, she, or they...?
You can certainly speculate that a he or she is gender variant if the speaker is alternating between these pronouns, or if his antecedent is a word like woman or hers is man, but if not, then you’ll only be able to know the referent is gender variant if this is actually brought up in the conversation, or is otherwise established knowledge. In which case you can’t really gauge how “cool” the he or she is just from the pronouns, nor how good an ally the speaker is, since for all you know, the he or she is truscum, fully passing and conforming to cis people’s standards, or maybe the speaker only selectively genders trans people correctly. Or if the speaker is alternating between masculine and feminine terms, then this may be because this is what the referent prefers, or it may be because the speaker is just bad at consistently gendering people correctly.
On the other hand, that they may be gender variant, certainly, or the speaker might just be unaware of that person’s gender, or perhaps doesn’t want to mention it, either as a “pronoun game” or as transphobic “degendering” or perhaps even as both. If it’s established that the referent is nonbinary, then maybe the speaker is just as glad that thon can stick to they and avoid calling more attention to the referent’s gender identity than necessary, and maybe the non-binary person themself doesn’t want their non-binarity to be acknowledged, because they don’t want to be associated with “that kind of enby”. You can't really tell from pronouns alone.
Which basically leaves us with just it and neopronouns. The pronoun it is in fact often lumped together with neopronouns and considered to be a neopronoun “in practice”, because a lot of people find it about as hard to convince others to call them it as call them xem. In the case of it, this is because it is a pronoun mainly used for non-human animals and inanimate objects, which makes people worry that if they call someone it that this will come across as degrading and insulting (note: tone and context can go a long way in clarifying the intent), or perhaps they as anthropocentrists (or as victims of such a society) just don't get why somebody would want to be called by the same terms as non-human animals, and would rather make that the referent's problem than sort through their own feelings.
All this being said, I'll conclude by saying that neopronouns have their own semantic space and pragmatic implications compared to the other pronouns that non-binary people commonly go by: mixing he and she generally implies mixing masculine and feminine, they is degendered, it is dehumanizing, but xe or ey or thon are unburdened by any of these established, conditioned connotations. The connotations of these neopronouns are first and foremost "the referent is probably nonbinary and very willing to stand out as such", and secondarily whatever associations people individually give to them.
Whatever you think of my analysis, I hope this has been interesting and a cause for reflection.
Side note 1: ''George Costanza behavior''
I think all of this also sort of explains the “George Costanza behavior” of people saying that they go by all pronouns but still “mentally ranking” people based on what they do with this information: they is -gender -trans, she or he is +gender -trans, and neopronouns are +gender +trans, and it follows from this that someone always calling you they might find it too uncomfortable to acknowledge that you have a gender at all, and on the other hand someone always calling you she or he might be able to comfortably acknowledge that you have a gender, but does not want to acknowledge that you’re trans/non-binary. You don't have to dislike being called any of these pronouns to be bothered by this.
Side note 2: The markedness of singular they
My own belief as a certified Armchair Linguist is that aside from serving as a pronoun for non-binary people, that singular they in reference to specific known persons primarily serves as a marker of social distance.
The evolution of singular they as I understand it (I may be wrong about the specific order) was that the earliest uses of singular they were with everybody as antecedent — due to the implied plurality — then with nobody, then anybody, then somebody; then this was further extended to generic nouns, then to unknown persons, then finally to specific, known persons. And as I see it, it makes more sense for this latest evolution of usage for singular they to be from "unknown person" to "barely-known person" — i.e. that singular they is a marker of social distance — than for singular they to have evolved specifically to serve as a marker of gender-neutrality, in a society that I observe largely does not care about respecting the wishes and boundaries of gender variant people.
This isn't to say that gender neutrality is completely 100% incidental to the usage and proliferation of the singular they, just that the gender neutrality is very much secondary to the evolution of they from plural to implied-plural to nonspecific to unknown to barely-known. Following from this, I would say the thing that makes the use of the singular they in reference to non-binary people so often marked, is that you're basically using a pronoun with connotations of social distance, in reference to someone you're socially close to.
For those who get called they against their wishes, this can really add another dimension to the hurt of getting degendered, because the implication is not just "I'm too uncomfortable to acknowledge your gender", but even "I'm uncomfortable with even just associating with you".
To be crystal clear: pointing this stuff out isn't meant to justify or excuse the people who don't want to call a they a them — those people are still just being transphobic and need to get the Hell over themselves. But I do still think that this helps explain why people end up using they in the ways they do, why people find certain uses of singular they more troublesome than others, and why some non-binary people like myself do not want to be called they.
Side note 3: Pronouns are a bad way to distinguish characters
There's an idea some people have that the reason why we have gendered pronouns in the first place is to help distinguish between characters in a story or anecdote or conversation, like ♫ it's all about the he-said-she-said bullllshit ♫ — but I find this idea very dubious, given how common homosocial interactions and relationships and institutions are, especially historically. It could very well be that it's actually more common for there to be two he's or two she's in a discourse, than a he and a she each.
By all means, feel free to call me xe if you're talking about me in the same breath as another she, if you feel this will make your utterance less ambiguous, but my point is that the evolution of language is a lot like the evolution of species: you can say that wings are for flying, but are they really? Wings are things that evolved under certain evolutionary pressures which are used for flying, but they weren't actually intelligently designed for any specific purpose. We have gendered pronouns in English as a vestige of the Old English gender system, whose roots go all the way back to Proto-Indo-European, and Proto-Indo-European evolved its gender system probably for complicated reasons involving grammaticalization and sound associations or something like that. Perhaps that gender system helped with the recollection of words, or helped with the comprehension of sentences that speakers of PIE didn't quite hear, but again, these are ways that these systems were used in practice, but not necessarily the reasons why these systems evolved — the system, with no-one intelligently designing it, never had any rational reason to exist.
If a language were being intelligently designed such that you could have two (or even more) characters in a sentence each be referred to with different pronouns, you would probably have obviation and reflexive possessives rather than something as unreliable as gender. Whether English will ever have these sorts of features, who can tell, but English in any case does not have these features at present.