I guess you are helping me make my point.
I do not think there is any basis for that - you didn’t list marrow, brain, connective tissue etc.
This limited list might work for you but, again, picking X, Y and Z out of nose-to-tail but trusting the research and studies based on nose-to-tail - might not be be a good long-term bet.
What I am wondering is whether skipping connective tissue would best be supplemented with glucosamine or skipping skin best handled with collagen.
I think if people - to get their “Carnivore” card had to either eat nose-to-tail or had to eat all of the necessary supplements along with their tasty muscle meat steaks - then it could be much better compared to other diets (in terms of compliance, effectiveness etc.).