Another gem is that in my local dialect the word for foot (Fuß) has an extended meaning and denotes the body part of foot and leg. There basically is not a separate word for leg (well there is but it's standard German not dialect). The standard German word for leg is "bein". Now Bein has a common ancestor with a similar word in English "bone", and indeed the dialectal version of Bein in my dialect is the word for bone. (To me that indicates that the word has made a meaning change in standard German).
Now if I don't think hard (or if I am tired) I will call my leg "foot" in English, which confuses everyone.
Probably in German both meanings were used alongside for a while and then folks started to attach a "ge-" in front of one meaning to avoid confusion.
(And then there are Platt (= Low German) and Alemannisch/Schwyzerdütsch, both of which are distinct languages from High German.)
Nonsense. If a native speaker uses a form and thinks it's correct, it by definition is.