Yes, Canon does a great job segmenting the marketing place but IMO fails to address some needs. I want 1Dx AF in a body with a crop sensor. Nikon keeps roughly the same AF in pro and pro sumer bodies. Canon does not, if you want great AF buy a 1Dx M2.
Canon does have pretty much the same AF in the 7D2 as in the 1Dx series - the difference is that the metering sensor is 150,000ixels as opposed to the 1Dx 300,000 pixel and from what I understand this is pretty much the as with the Nikon D500/D5 models. So I am not sure what you mean that Nikon do something that Canon does not.
I along with many other photographers I shoot with, all have said that the 1Dx M2 AF is significantly better than the AF in the 7D M2.
On a recent shoot of flying raptors, I compared the keeper ratio between my 1Dx M2 w/ 200-400 vs Nikon D500 w/ Sigma 150-600 contemporary - the Nikon won.
I agree. But what did you expect that when the metering sensor (which is used by the AF) is half the size, the battery is significantly smaller and it has only one processor to do AF and other functions? Unless you can show me otherwise, I believe the same comparison applies to the D500 vs D5.
And I have also heard many times that the D500 is better than the 7Dii for tracking birds in flight, but that does not mean the D500 is any more similar to the performance of the D5 than the 7D2 is to the 1Dx2.
It's more than just what a manufacturer "decides" to give each model. The physics involved will always constrain the PDAF system in an APS-C camera more than the exact same technology in a FF camera.
The larger sensor of a FF camera, and the resulting wider mirror size which allows a wider semi-translucent portion of the mirror, allows a wider baseline for the PDAF system.
It's more noticeable when comparing APS-C and FF Canon cameras because Canon tunes many of their AF points to operate at wider apertures in order to give them more sensitivity. Nikon tends to tune most of their AF points to work with narrower apertures in order to make them usable with more lenses. This makes the difference less noticeable when comparing the performance of APS-C and FF Nikon cameras.
P.S. What is a Canon 1Dx or 1Dx2? Do you mean the Canon 1D X and 1D X Mark II? Dx is a Nikon thing designating an APS-C sized sensor or a lens made to cast an image circle size for such a sensor.