I think the first citation in the comment you link to gets something wrong. It states that there is a correlation "very closed to zero" between actual performan

I think the first citation in the comment you link to gets something wrong. It states that there is a correlation "very closed to zero" between actual performance and perceived ability. If you take a look at the paper, it addresses that. The better-than-average heuristic accounts for the compression you see, and once you remove it's effects from the picture, the correlation appears.