Why are there unusual word meanings and phrasing that are completely unattested in either Joseph Smith’s time or in the eighteenth century, yet can be commonly found in the centuries before that time?

In addition to the Book of Mormon containing archaic syntactic patterns, Royal Skousen and Stanford Carmack have also shown that the Book of Mormon contains word meanings and phrases which are unattested in Joseph’s time yet are commonly found in the centuries before:

break (to stop or interrupt), but (unless, except), call of (need for), consigned that (assigned that), counsel (to consult, counsel with), course (direction), cross (to contradict), depart (to divide, separate, part), desirous (desirable), devour (to consume, eat up), extinct (physically dead), flatter (to coax, entice), give (to describe, portray), idleness (meaningless words or actions), manifest (to expound, unfold), mar (to hinder, stop), nithermost (nethermost), opinion (expectation), profane (to act profanely), raign (to arraign), scatter (to separate from the main group), sermon (conversation, discussion), study (to concentrate thought upon), subsequent (consequent), welfare (success), whereby (why)
– Stanford Carmack and Royal Skousen – Revisions in the Analysis of Archaic Language in the Book of Mormon

Why would these words (and unusual meanings) be in Joseph Smith’s vocabulary?

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