That paper was thoroughly rebutted when posted to HN. But Gwern has written about some earlier debunkings of the D-K effect, ad furthermore D-K was never about

That paper was thoroughly rebutted when posted to HN. But Gwern has written about some earlier debunkings of the D-K effect, ad furthermore D-K was never about the popular misconception of D-K ("incompetent people think they are more competent than competent people").