the talking point i see a lot, most recently in that Andrew Sullivan op ed on 'gay rights going too far', where people say 'i support nonbinary people but how many genders can there be? this is out of hand' etc i think in this case he said there are 'up to 70'.
the reason it sounds so silly is because there is no 'quantifiable number of genders'. gender is infinite and unknowable. engaging with this inane question shows that no actually you don't support nonbinary people. this is just a repackaged version of the right wing doubling down and even trying to enshrine into law that there are only two genders. which you can't. it's like trying to legislate sand through your fingers
still keeping with Sullivan's piece as an example, much of the resistance to solidarity with nonbinary identities (and other queer stuff but it's nonbinary people's day so) is about "Now they're demanding that i call them by singular they or a neopronoun. now this community (that i am seeing as a monolith) is policing my words! they are demanding i respect something they made up and i think is silly!" the threat being, i don't know, that they get 'cancelled'? which doesn't really exist in any meaningful way?
a lot of identities people seem extra obtuse about are imperfect attempts to describe an immensely personal feeling, and really it's kind of nobody's business if you understand it or like it and you don't actually need to understand it to treat folks how they want to be treated. it's possible to not be a cop about other people's identities.
Sullivan and others blame the 'weirdest' among us for setting back queer rights and "making the community look bad" when they could just knock it off, and have a scrap of solidarity against the fascists who are the real threat, and realize that it doesn't matter how respectable you are, they are coming for you next. the idea of who is nonconforming is a moving target.