Put another way, it took Nikon two generations to come up with a camera that approaches the 5DIII in overall utility...and I bet the 5DIII outsells the D810 just as it did the D800/E.Errrrrrr I don't think we are talking sales figures here but camera technology. Precisely where does the D810 not exceed a Canon 5DIII? Nikon D810 exceeds the 5DIII in any reasonable comparison. In quality of the sensor it absolutely trounces the Canon. lets not distract the conversation with lens line or spots on the D600 sensor and stick to the comparison between the 5DIII and the D810 bodies. The 5DIII "approaches" the D810 in some respects...but exceeds it in none. BTW I own and love the 5DIII but it is outclassed by the newer D810. Yes, Canon is 2 generations behind, at least on sensors and it doesn't look like that is going to change anytime soon
Same thing one step up – it took Nikon until the D4s to approach the 1D X.
I see you also believe that the only important part of the camera is the sensor.
Ooooh, look at that amazing bird-in-flight shot from the D810...incredible resolution, really wide dynamic range. Sure, it's a bit blurry because the AF couldn't track the subject well enough...and just a little off optimal wing position where maybe a 20% faster frame rate would have helped...but just look at the DR and all those MP.
Camera ≠ sensor.
As stated earlier, the 5DIII has a faster frame rate and a better AF system, to name two camera technologies where it is superior to the D810. The D810 has better low ISO DR, great if you need it. It has more MP, although with many lenses that doesn't translate to better resolution (and when it does, the difference is much less than the MP differential would suggest). You may view lenses as a 'distraction', but unless you drill a pinhole in your body cap, lenses are necessary.