Lemmy without politics is kinda a ghost board. There is maybe 3 or 4 new posts a day.
I think your approach of blocking any user who posts about politics is eliminating the most prolific posters when 95% of their stuff is non-political. This is not to say your approach is bad, just that it doesn’t actually represent “Lemmy without politics”.
I’m not sure how you come to that conclusion, even with the internet meme version of the Dunning-Kruger effect. In the meme version, the incompetent think they are most competent, but I don’t think it follows that the most competent would think they are least competent.
I would summarize the actual Dunning-Kruger effect as: people tend to think they are a bit above average, and actual skill factors in only slightly. Worth emphasizing that these results are over groups of people, and individuals have extreme variation.
https://en.wikipedia.org/wiki/Dunning–Kruger_effect