I do agree... but as long as the correct viewing distance is maintained for the image size all should be equal... My comments are based on my years at college for my C & G 744 in general photography and IIP intermediate (back in the 70s), one of the exercises using a Gandolfi 5 x 4 (I am sure Terry will remember them) was to photograph a ruler at an oblique angle maintaining sharpness and perspective using the camera movements. My whole point that I was trying to make is that using tilt only tilts the plane of focus, the DoF remains the same (although there is a bit of discussion as to whether it widens slightly towards the horizon.
Langford was quite clear in Depth of Focus is at the film/sensor plane and Depth of Field is the distance from the nearest point of acceptable focus and the furthest and the two terms are not interchangeable.
I should add I do not have an engineers thought processes so look at things probably differently to yourself and probably less analytical