A very easy way to square all this (and what I assumed everyone understood to be going on before I ever heard of this discourse) is that people are just using exaggeration for emphasis (a very common rhetorical tactic).

Of course people aren't saying it's literally thing-they're-referring-to but that it has so much in common that it's "practically" almost exactly that thing.

I feel like people overcomplicate what needn't be complicated, sometimes (like people hallucinating a "fourth-person" pronoun to explain a convention perfectly already provided by current linguistical constructs).

They didn't just utter it. They wrote it down, thus making it canon to language lore. 😌

The notion that “just because someone lived a long time ago, they must have been backwards, ignorant, or stupid” is one that needs to die a loud and public death. It is that line of thinking that leads people to believe that aliens built the Pyramids, Stonehenge, etc. because they are certain that folks back then weren’t clever enough to move large rocks about.

He is a fortunate man to be introduced to such a party of fine women at his arrival; it is literally to feed among the lilies.

-- The History of Emily Montague, by Frances Brooke, 1769 (emphasis: mine)

The use in the figurative sense isn’t valid merely because of “some rando uttering a word” a long time ago. It is valid because it continued to be utilized with that meaning for the next 250 years and is still used and understandable in that sense to this day.

Citing some historical rando is as descriptivist as it gets.

The opposite of what? I’m curious how you interpreted my words, because that quote does not contradict any claim I intended.

Correct! It’s called a contronym, it is such a normal thing in language that they made a word for it.

Plenty of words mean the opposite of themselves, so much so that there's multiple words for it; autoantonym, contranym, or Janus words.

This morning my alarm went off so I turned it off.
I wanted to buy a new console as soon as it was out but they were all out.
Two people were left so I left.
I fought with Bob over chores, but I fought with Bob in the war.

Or a letter from my college saying that my club has been "sanctioned".