SteveR I'm afraid you're the one who needs to think this through again, although this issue has been discussed, and resolved correctly, countless times on UHH.

Although a lens of given focal length projects an image of the same size on the image plane of a crop sensor or a full frame DSLR, cropping in PP with a 24 or 36 Mp full frame sensor results in image that includes fewer pixels than an uncropped image with the same lens on a 24 Mp crop sensor camera such as Nikon D7100 or D7200. Here's the math for a crop factor of 1.5. When cropping that much with a FF camera to match the uncropped view on D7100, you reduce the number of pixels by a factor of 2.25. That leaves 10.67 Mp on a D750 (24 Mp sensor) or 16 Mp on a D810, compared to all 24 Mp on the D7100. That means better resolution and more detail with the crop sensor camera. The "reach" advantage of crop sensor is real, so long as the crop sensor has high enough pixel density.

But for D750 owners, such as myself, the D7100 or D7200 edge in shooting, for example, distant wildlife with a particular tele lens is even greater, since the D750 has an anti alias filter that slightly blurs the image, while the D7100 and D7200 do not.