It sounds like part of the problem he had was the fact that he was using adapters and lenses not designed to work with the camera. While I'm sure these lenses are amazing, if they aren't designed to be used with a specific camera in mind, they don't produce the images they are capable of. Same with the camera. I have found from personal experience that adapters can cause all kinds of issues, so I stick to the mount that the camera has.
I would have loved to see a bit more dynamic range, however Canon has come a long way with ISO performance with this camera and the 7D MK II as far as banding and shadow noise.
I wonder how different the review was if he had maybe the Sigma 50 1.4 Art, Sigma 35mm Art, Canon 11-24 f4 and perhaps the Canon 70-300L, which he mentioned but I don't think he used. Or even the 70-200 f2.8 II. It was a good review, but I think because of the use of adapters, manual focus and live view, its not a good representation of what the camera is capable of. I would say the vast majority that invest in this camera will be using EF mount lenses.