Have you not just summarized the Dunning-Kruger effect in other words?

That essentially follows from everyone assume they are slightly above average. That's also the crux of the refutation and why the whole autocorrelation is a red hering, even if we all would just self assess completely randomly, that actually confirms the Dunning-Kruger effect is real (because if we self assess randomly worse performance are more likely to overestimate).

We could argue that this is not surprising, but the "surprising" bit is that the curves show that better performers are actually more skilled at assessing their performance, which incidentally was also confirmed by the followup studies.