It's a mixture of misrepresentation and denigration.

I think you’re confused. We’re talking more about the kind of thing where there’s a distinction between a “programmer” and a “programmer’s programmer”, where being too much of a programmer (i.e. a “programmer’s programmer”) makes you less like a “programmer.”

The noncentral fallacy is somewhat opposite to that—MLK is certainly not a “criminal’s criminal”—the reason people don’t identify him as a criminal certainly isn’t because he’s too much of a criminal.

My point was more that, in this case, she is “just a librarian”, because this type of thing is what being a librarian is supposed to mean—it’s just that most people suck at being librarians, kind of cargo-cutting the actions librarians have traditionally taken rather than looking around and trying to embrace the spirit of the goals librarians try to accomplish with the highest ROI possible for a modern context. When “librarian” was invented as a term, it referred to people like this.

The same is true of Dennis Ritchie: he’s just a programmer—because the word “programmer” was originally invented to describe people like Ritchie. But by that same historical standard, most modern “programmers” aren’t; they’re just code-monkeys.

The Usain Bolt example is different—Bolt really is an exceptional runner, rather than being a denotationally-central example of what it means to be a runner. When the word “runner” was invented, it referred to the lesser thing, with plenty of central examples; and by that yard-stick, Bolt is more like a “super-runner” or some such. (Similar to how the word “food” developed to refer to a category where the central examples were nutritionally merely-adequate, so now we’ve had to invent the word “superfood” for foods that are, like, really dang good at being food.)