Regardless of whether Dunning-Kruger is real the solution is the same. DK concerns poor performing people who cannot accurately address their performance relative to a group. Forget DK. The bigger problem is missing objectivity, which is a very real concern. So, just measure for objectivity.

Can they measure things or do they just guess? Are they willing to seek evidence? Even if evidence is immediately available will they use it? Everybody has bias, but is their bias primarily self-oriented?

The consequences for poor objectivity are profound and measurable, but then its an invisible failure for people that struggle with this in the first place. In many industries poor objectivity can result in termination, law suits, criminal penalties, physical harm, and more. Software just seems to pretend this is vapor.