The linguists are fond of saying that dictionaries are descriptive, not prescriptive. They tell us how words have been used up till now, not how we're supposed to use them. If enough of us use a new word it gets entered into the dictionary.
Language is always changing. In King James time when they translated the New Testament they used words like "thee" and "thine" because 200 years earlier those were common words. But in King James time they were already using "you" and "yours" out loud. They just hadn't changed the spelling yet. "Thee" was pronounced "you". Later the spelling also changed.
As for us Americans butchering the English language, there was a TV documentary by Melvyn Bragg, an British historian and linguist and writer, called "The Adventure of the English Language" in 2003 and in one of the episodes he said that the southern states in the USA speak what is a lot closer to the English of the 17th century than is spoken in England today. It's those Brits that are butchering our English.
He also mentioned that over 50% of the English speakers in the world are in India so if we want to be democratic and let the majority rule, they're the only ones getting it right. The rest of us are butchering our language.
Barry