What has Canon sales to do with DXO ?
Nothing. Which is exactly my conclusion:
So, DxOMark has said Nikon has had better sensors for years, and the sales data show that Canon has sold more dSLRs and lenses for those same years, and continues to do so, as of the most recent data available. The straightforward conclusion from the above is that while DxOMark's Scores have a huge impact on the number of inflammatory posts on Internet discussion boards, they have no meaningful impact on the real world aggregate buying decisions of consumers.
If Consumer Reports gives one product a much higher rating that another product, that usually has a tangible impact on sales, i.e. those reports impact buying decisions. DxOMark has given Nikon higher ratings than Canon for years, and there does not appear to have been any impact of that on sales, i.e. they have no impact on buying decisions.
a) there are flaws and ambiguity in their scores, not to mention some apparently aberrant results (e.g. 70-200 II),
b) their scores apparently (according to them) should not be used to compare cameras of different resolutions,
c) they are scoring only sensor performance, which is just one part of camera performance,
and d) the reduction of a complex imaging system to a single number is essentially meaningless anyway,
I would argue that not only do DxO's Scores have no impact on buying decisions in aggregte, they should have only a minor impact, if any at all, on personal buying decisions.
As I've pointed out before, their measurements are usually quite good (I say usually because of the above-referenced 70-200 II issue, where DxOMark are the only ones in the world who seem to think the MkI is better than the MkII, and chose not to test another copy but rather to defend their results, which really doesn't help their credibility). But their Scores are neither meaningful nor useful.