I think the thing is that common concepts have common terms, often short and well-known. Why invent a new word when a good term exists? Sometimes you do need a new term, but by definition the thing you'd describe isn't 'common'. E.g. I like this depiction of a Ph.D. matt.might.net/articles/phd...
Sometimes we talk about things that are not common as if they are already common (e.g. the famous XKCD xkcd.com/2501/). That's an impedance mismatch at best, and at worst can actively drive people away by signifying that they're not already part of the club.
Long before this was part of the culture war there was a concerted push to write legislation, regulation and policy in "plain English" as much as possible, because a democracy is made stronger when people are not artificially excluded from the discussion through choice of language.