The Dunning-Kruger effect says that, if you're stupid, you'll think you're smart, and if you're smart, you'll think you're stupid (or, at least, "equal" or "similar"). That applies, though, only in cases where people haven't already heard of the Dunning-Kruger effect: people who are aware of the effect will, if they're somewhat stupid, have the potential for more accurately estimating their own inferior capabilities, while if they're smart, more accurately estimating their own superior capabilities.
In a world where no one had previously observed the "Dunning-Kruger effect," the DKE initial test(s) might've had significant merit to affirm the DKE. But what does it mean if someone, having heard of the DKE, subsequently begins to report her own results less modestly than otherwise, based upon her realistic assessment of, say, her IQ relative to that of the average test-taker on campus? For the initial tests, too, what about people who were so smart that they had already figured out the DKE on their own, as people have from time immemorial? And how does that interact with the higher-IQ bourgeois tendency to have been pedagogically required to self-report modestly, contra the less-educated prole tendency to grandiose self-reporting in order to obtain success in different types of life?
Dunning and Kruger were, no doubt, clever enough to have considered all this, so they rigged their little test to prove the point they wanted to make anyway. Well, for all that effort, they get to name that planet.