Originally posted by Jyn
[Double negatives are ] evidence that the breaking of such rules stems from relatively uneducated ignorance. The rule on double negatives, in theory, is one of the most basic and important rules of language. Sure, everyone knows what you meant in practice, but that isn't what you said. It should be -simple- logic.
Only if you assume incorrectly that the writers of Old and Middle English were uneducated and ignorant. Most of the Old English scribes were monks - the most educated people in the society. They also made frequent use of triple and other multiple negation.

"Ne no schafte ne no schelde to schwue ne to smyte" - Sir Gawain and the Green Knight. ("neither no shaft nor no shield to show nor to smite")

"Ne this ne may nat be wi seid in no manere" - Chaucer. ("and this cannot be denied in any way").

They're frequently used in modern English as well, where some extremely well-educated people used them with regularity.

Oliver Cromwell wrote in a letter from 1644. "...that God had not suffered him to be no more the executioner of His enemies."

Shakespeare used them often, "no woman has; nor never none shall mistress be of it..." - Twelth Night.

And present day English, "I have neither the need nor the desire" is double marked as negative (neither...nor), but considered required by the standard prescriptive grammar rules.

It's only illogical if you assume that mathematic "charges" have anything to do with language. And if this were the case, then triple negation should be "proper". Yes, it's redundant, but so is the sentence, "yes it's redundant".

"That ain't no joke." Most people (including the speaker) assume they mean the issue is serious, when in fact they're saying the opposite. This kind of ignorance can only be detrimental to human communication.
If most people understand it's meaning, how is it detrimental to human communication?