Snapsort - Canon's poor image quality ratings compared to competitors?

I like to compare stuff on snapsort all the time, so I can look at the technical features side by side.

I noticed that in there ratings and recommendations, Canon DSLR's have the worst image quality ratings compared to the competitors at the same price point.

Does anyone have any insight as to why Canon, one of the major names in photography, is behind Pentax, Sony, and Nikon in overall image quality?
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-Paul