I suspect that plunging in and making a poor argument doesn't reflect well upon you. I am happy to be corrected, if you can provide a rock-solid reference: the English language is a wonderful midden.

> late 14c. (from c. 1100 as a surname), "a worker in any sort of lead" (roofs, gutters, pipes), from Old French plomier "lead-smelter" (Modern French plombier) and directly from Latin plumbarius "worker in lead," noun use of adjective meaning "pertaining to lead," from plumbum "lead" (see plumb (n.)). The meaning focused 19c. on "workman who installs pipes and fittings" as lead pipes for conveying water and gas became the principal concern of the trade.

We can read Vitruvius' description of chorobates at https://penelope.uchicago.edu/Thayer/E/Roman/Texts/Vitruvius... (Note that https://ethw.org/Roman_Aqueducts claims "the credit given to this instrument by Vitruvius was out of proportion to its real usefulness.")

> The chorobates is a rod about •twenty feet in length, having two legs at its extremities of equal length and dimensions, and fastened to the ends of the rod at right angles with it; between the rod and the legs are cross pieces fastened with tenons, whereon vertical lines are correctly marked, through which correspondent plumb lines hang down from the rod. When the rod is set, these will coincide with the lines marked, and shew that the instrument stands level.

The Latin for "plumb lines" is seen in "quae habent lineas ad perpendiculum recte descriptas pendentiaque ex regula perpendicula in singulis partibus" - Vitruvius does not use a variation of "plumb" to describe those verticals.

That usage, from the quoted etymology, wasn't created for another 1,000+ years.

I could be wrong of course, but the evidence I've seen doesn't support your claim at https://news.ycombinator.com/item?id=33765351 .