Look at the chart in the article. Let's say actual ability is x and perceived ability is y. The graph effectively asks us to compare the difference between perceived ability and actual ability, which we can write as y-x. Thus, the chart effectively graphs y-x over x, which can be written as -x+y over x. There is always a strong correlation unless y approximates x.
IMO, the conclusion of that analysis should be "Dunning−Kruger is a truism", not "Dunning−Kruger doesn't exist".
https://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect#Statistical_and_better-than-average_effect