So, yeah...

An interesting and potentially highly useful term coined by TVTropes: Dead Unicorn Trope. (For those who don't want to get sucked into six degrees of TV Tropes, we'll summarize: What distinguishes a Dead Unicorn Trope from a Dead Horse Trope/beating a dead horse is that the "straight" form of it never actually existed in the first place. Or at least nowhere near as widespread as it was claimed to be. "The butler did it" is a classic example, because there never actually was a trend of mysteries in which the butler did it being a hugely overused cliche.)

...the overall concept reminded very much of some of the things we were trying to describe in this post. Particularly the spreading around of claims like "this person claims to be LFA!" until they got to what we described as having the status of an urban legend, the only difference being that they were about real-life things and not concepts in fiction. And a lot of beliefs like that seem to accumulate around disability in general-- both about what people with various types of disabilities do and don't say about themselves, and what they ask for/want/think is a reasonable accomodation. Ideas about the Americans with Disabilities Act leading to some massive wave of frivolous lawsuits filed by people who just wanted to get rich, for instance. And of course the whole idea about "people just say they have Asperger's because they want an excuse to be rude/because it's cool/etc!", and we've... already explained our position on that in great detail in the replies to this post.

...oh yeah, I guess it wouldn't hurt to mention that the posts by someone called "farmwifetwo" in that thread are potentially triggery for how they describe an autistic child, and claims of all autistic participants in the thread being "too high-functioning" to know the real reality of autism, etc etc blah blah. Which is made all the more ironic by the fact that later in the thread she's going "zomg your parents destroyed your medical records omg that's so horrible what kind of person would do such a terrible thing!" Um... welcome to the real reality of being an autistic adult? As Larry pointed out further down in the replies, it's not uncommon for medical records to be lost and destroyed for any number of reasons. And we know just based on anecdotal evidence-gathering that we're far from the only autistic adults whose parents went to extremes to, in some way or another, hide their childhood "strangeness" and any associated diagnoses from them and the rest of the world. We can't tell anyone what statistical rate it happens at, we just know that we're by no means any kind of unique, isolated anomaly when it comes to that.

(Meanwhile, we also wonder, in an abstract sort of way, what kind of parent could do a terrible thing like declaring that their own child will never have any skills and no future outside of an institution. I mean, we know it happens, because people do it all the time. We just can't understand the kind of thinking and perceptions and deliberate ignorings that would lead to that conclusion.)

But... I guess the whole concept ties in, in our own thoughts, to a much broader phenomenon we've noticed about these ideas about people or (assumed) types of people, who are claimed just by word of mouth to do or say or believe some thing that of course any reasonable/sane/etc person would see is ridiculous and awful and bad and horrible. (...sort of sarcasm there, because we've been in unpleasant social situations in the past where we had certain things basically shoved in our face and treated like we had to put them down or mock them or make some big statement about how terrible they were, the idea being that every okay/sane/good/etc person should feel that way about them. When we didn't in all cases even see what the problem was, or we thought the person/people in question were being badly misrepresented.)

And how ideas about people can just grow and grow through endless repetition and appeal to outrage, until "everyone" knows that a certain person or group does or thinks a certain thing, when that supposed "common knowledge" in no way resembles the reality. We were poking at ideas for a conlang recently and thinking about the role of evidentiality in language, and the concept of a culture in which linguistically marking a certain idea as common knowledge might be seen as rude or questionable. Also some of the ideas we've seen that get circulated around about plurals or certain types of systems, including one that we had to rebut yet again on a community recently. Also how some of those confusions might result from lack of linguistic markers in English to distinguish between subjective mythic experience and tangible physical experience, but that that doesn't necessarily excuse people for taking ideas of "all X think Y" and holding people to an idea they may have never actually subscribed to.