I believe you may have picked the one language which inadvertently illustrates my point.
My understanding is that Python does these things because it's in the SAME bag as JavaScript: it's actually a proto language in implementation down deep, but with a class-based syntax, thus inheriting the disadvantages of both and the advantages of neither. There's some dynamicism bubbling up from the object implementation but it's a far cry from the elegance of a real proto language. I do not know why Guido chose to do this awful thing, but he is at least to be excused given the age of the language. JavaScript has no such excuse.