You think you are good at chess because you win against your neighbour, then eventually a class mate absolutely embarrasses you multiple times and you realize there is a whole world you don't know, and before now you didn't know that world existed. Then you eventually beat your classmate before getting whomped by the beginner in the chess club and the whole cycle happens again. After this happens a few times, you should begin to find each time less surprising than the last.
To me this is the essence of DK and not really something to be proven/disproven by maths. You don't know what you don't know, and it takes some learning before you are wise enough to realize there are unknown unknowns.
> instead showed that both experts and novices underestimate and overestimate their skills with the same frequency. “It’s just that experts do that over a narrower range,” he wrote to me.
I think this is trying too hard on the researcher's part... if the data were reinterpreted such that small estimation errors are considered correct then the effect would reappear.