To say a very fine course in one region is .01 better than a course in another region that is only defined as "best modern" or "best classic" or "best world" is futile without narrative.
Thing is, that's not what those rankings say. As I understand it, they simply RANK the courses. They don't say how much better one course is than another. There could be a huge difference between the courses ranked 9 and 10 in the raters' minds. Or there could be next to nothing.
One example of this is the Mohs hardness scale for minerals. Diamonds are ranked 10, the hardest mineral known. Rubies are 9, and talc is 1. But diamonds are not 11% or so harder than rubies. They are four times harder. They are 1600 times harder than talc. The Mohs scale completely obscures that, though. Just like saying Tiger was the #1 golfer in year 2000 obscures how much better he was than #2 and everyone else.
Golf Magazine and Golf Week, I believe, make it even harder to draw absolute conclusions because they rank the courses in groups. To get a score of 10, a course must be among the top 3 (or 5 or whatever) in the world. That doesn't even tell you how the courses rank within the category. An example would be if the Mohs scale gave a score of ten to the two hardest minerals. That would rank diamonds and rubies the same, even though diamonds are in fact four times harder than rubies.
The Doak scale does the same thing. Maybe I'm wrong, but I doubt Tom personally considers all the courses he ranked 10 to be as good as each other. He probably considers some better than others. Same with the 9s, 8s and other scores in his guide. But there's no way to know.
How much better does Tom consider Pine Valley than Shadow Creek? About 11%? I don't believe there's anyway to know from the CG. Same is true of the rankings in GM and GW.
As for Ronald's question: people rank almost everything. Restaurants. Hotels. Cars. Kitchen appliances. Computers. TVs. Singers. Songs. Guitarists. Guitar riffs. Actors (academy awards). Football teams. Golfers (Tiger, Jack or Bobby?) Golf course architects (Ian Andrews' interesting list and articles are one example). The list goes on and on.
Who is the best? Ranking tries to establish that. When there's an objective measure -- like running 100 meters -- it's not so hard. When things are subjective -- like art, music or golf course architecture -- we can have lots to talk about.