I was just thinking this, i was wondering if there is much difference between saying gnc and non binary? I think there is but I can't articulate it so I'm going to think this out. I think gender may be an exception because it's so pervasive in the life of every human being whether or not one conforms to it. It probably has a lot more to do with how people use the label. Gender non conforming is exactly that, a person that does not perform their proscribed gender. Does non binary perform the same function? It seems to imply they are outside the system rather than rejecting it. And which binary, male/female or masculine/feminine? They don't really make a distinction. GNC people are still male or female and socialized accordingly even if they don't conform. I think the rejection is important there, stating I recognize society want me to be a certain way but I refuse as opposed to saying that you're neither and it doesn't affect you. GNC is a useful word because it describes a certain group of people who are descriminated against. GNC people are usually bullied for not conforming. GNC children are often (but not always) gay. We as feminist may reject being forced to preform femininity but at the same time most of us still do, so it wouldn't be accurate to describe all who reject the gender roles as GNC. But nonbinary has not developed into a useful label, as anyone can just decide to apply it to themselves rather than it being a descriptor of them. It seems to apply to people who just want they/them pronouns but are otherwise not what we would call gnc.

Tl;dr I don't think it's perpetuating it so much as just describing it. In the ideal future, words like gnc, masculine, feminine, even gender, wouldn't exist. But since most people on the planet believe in gender one way or another, we have to be able to describe this particular type of person.