Thank you for explaining this misunderstood fact in the development of English. I always liked using the double negative, at least in certain ways. Then when I learned that it played a significant role in the development of the English language, a most remarkable language IMO, I have valued its use all the more!
This isn't a double negative but an example of wonderful English I found in Arizona when I asked where a friends sister was:
"She done did got herself home," was the reply.
Isn't that better than "She is home"?
There is a road in my Connecticut town named "Roast Meat Hill." 100 years or so ago, a hay wagon caught fire on the road and the horse team pulling it perished. Tell people you live on "Roast Meat Hill" and they never forget it. So much better than "Garden View Terrance" or "Maple Street."