I've noticed that many individuals here assume negative tone in what are actually neutrally toned statements unless you add overly descriptive language to ensure neutral tone. It's not great and leads to echo chamber style communication and overly pedantic arguments often.

I don't think it was intended to be negative, just a reference to this XKCD https://xkcd.com/1053/

Even when something is known by "everyone", there's still going to be someone who doesn't know it yet.

I never heard about this fable before, either...

I believe you have misinterpreted something that was a reference to xkcd with purely positive intent. At least, the original has that intent and I'm assuming that is reflected here.

This is a community that values a high signal to noise ratio and generally eschews small talk, a la nohello.org. Congratulating someone for learning something does not advance the conversation.

It also has a low tolerance of what it perceives as reddit- style in-group signaling via repetition of a common meme (xkcd, in this case). Again noise vs signal but also suspicion of karma farming.

I think most people here are aware of the 1 in 10,000 reference, but it can come off as belittling because it implies it is knowledge most people know.

I think it's usually used for stuff that is assumed to widespread or even common knowledge.

In this case it's about a not-mainstream publication with a non-obvious reference as a name. (also fwiw, I'd bet the knowledge of the term for non-native speakers is even more obscure). So I would interpret the downvotes as "misuse of expression" but I can only guess ;)

it's an XKCD reference: https://xkcd.com/1053/