This is getting exhausting! I finally looked through Theory of the Photographic Process, the later edition (James) as referenced by Mark Barendt.
This idea that "the preferred print has less density than the subject" seems to be at the heart of these disagreements. Anyway, I DID NOT find this stated in Theory... However, it is possible to misinterpret this from a graph if one doesn't notice the base point of the reference lines.
There is one place, page 539 (James' edition), that says, "It is significant that the densities of skin tones in the preferred prints were found to be equal to or slightly lower than the densities of real skin" [emphasis is mine]. Again, "equal to," or "slightly lower." In the Giorgianni graph, they are shown as roughly equal, as I pointed out in post #55.
To conclude, I don't find any statements to the effect that a print needs to be lighter (less dense) than the original. (I agree there are cases where this works well, just not that it is stated to be a requirement for preferred prints.)