Just based on the graph just under the "The Dunning-Kruger Effect" section, one observation I'd like to present is that the subjects's numerical self-assessment

Just based on the graph just under the "The Dunning-Kruger Effect" section, one observation I'd like to present is that the subjects's numerical self-assessments fall into the same range as passing but non-stellar grades do in school. This may reflect a psychological bias in how the subjects use and understand percentages. Accordingly, that the two lines cross is a red herring.