It's a common refrain from those who don't like how DxOMark rates their favorite camera/camera brand. Not only does DxoMark disclose their methodology, their results have been independently reproduced by individuals who have done their own sensor measurements. Lenses are a different story - DxO's methodology for its lens testing is a big black box.I'm no photographer, but I've heard from a few in my company who work in the camera business that they wouldn't rely on this company for reviews. I'm not sure if it's due to their methodology or because they're too easily influenced by money they get from the manufacturers or both. Maybe some photographers on here can shed more light.
One thing they could have done better is to categorize the phones by size. Larger phones have more room for better sensors, lens, etc. and that's been the trend for a few years now. Lumping them all together is like including point and shoots with DSLRs.