there are 2 discussion threads about this. no point of starting another one and diverging off the course of OP's original point of discussion.
the short answer to your quesiton is that they probably dont have time nor have the will to do every SKU comparison. AMD will be called out in comparing 5800x against 10700k cos people will say, hang on it is $$$ vs $$ not fair etc. so the best they can do in a fair way is to compare top sku vs top sku in a normalised way ie 5900x (12c) vs 10900k (10c). i think AMD has done fair here, if it is intel they would have used the 5950x to blow the 10900k out of the water, as they will just go straight to their best SKU vs AMD's best SKU regardless of price, core etc.