I found it interesting.
The hay and veggie diet seem to be mostly tailored toward small-type, non-breeding pet rabbits which tend to not require anywhere near the amount of calories that larger type, faster growing types may require.
I disagree with the statement that the best diet for all domestic rabbits is as close to a wild rabbit's diet as possible. My logic being that our domestic rabbits, especially fast growing commercial types, do not have the same metabolisms as wild rabbits.
For comparison, in regards to wild european rabbits (Oryctolagus cuniculus)
wikipedia states:
Weight can range from approximately 1.1 to 2.5 kg (2.4 to 5.5 lb)
Some domestic rabbits can reach 5 lbs in as little as 2 months, and potentially grow up to 20 or more lbs.
I'm positive that type of growth only ever becomes possible on diets with caloric sources not commonly available to wild rabbits.
If you count grass and seeds as grain though, wild rabbits may actually eat quite a bit, especially in winter.