Here again it would be great for everyone to just put up their definition of natural. Somehow, I think a few are in the Melvyn Morrow camp and are talking pre 1900 almost nothing to design.
Some others may talk Mac, but in truth, his courses are built. The greens, tees, and bunkers all had fill moved. He shaped mounds and cut fairways for dirt and vision. He just didn't do it as boldly with horses as later architects did with bulldozers, but the though process of building was almost exactly the same.
You could argue his puzzle piece bunkers, which BTW have probably set the modern standard, are the least natural, most contrived pieces of golf design artwork ever, no? Natural gullies rarely have that great form in just the right place, LOL.
And of course, its great architecture, in the eyes of most.