Interesting article, but way too complicated to read at the end of a long day.
The easiest way to visualize this is to look at the ancient history of the Old Course at St. Andrews. Most accounts have the course beginning with 12 holes in the ground arranged linearly, roughly in the shape of a 2 mile long backwards question mark. Play began next to the first hole in the ground, hitting toward the second hole in the ground. Tees were not invented until much later, so players would elevate the ball for their first shots with a pinch of sand. As each hole was finished, play to the next would begin immediately adjacent. Upon reaching the 12th hole, play would reverse back to the first hole. In total, 12 holes in the ground, 22 holes of golf played, 11 forwards and 11 reverse.
Three problems were soon evident as the game became popular. One is that all the little sand tees made a mess of the rudimentary putting surfaces. Eventually, the teeing zones were moved to a specified area about 10 or so yards to the side of the holes in the ground. Second, the holes would wear out and regularly need to be moved and re-cut. The third is that the going out players and the returning in players were constantly getting in each other's way. This was solved by enlarging the rudimentary putting surfaces and putting two holes in each of them for out and back, creating what we now call double greens (except the first and 12th holes in the ground, which were only used in one direction). Over time, the fairways also enlarged and split to better aim towards each of the two holes in the ground. At this point, the course could be played either counterclockwise (now the standard way) or clockwise (originally done every other day, but still done one day a year for historical amusement), hence the concept of a reversible golf course.
As equipment and golfer skill improved, some of the shorter holes were combined and the course shrank from 22 to 18 holes, the standard worldwide ever since.
If you play the Old Course now, you will notice many holes still have tees immediately adjacent to the greens, usually the white or red tees, since the championship tees have been moved back and/or angled several times over the years as equipment and distances improved.
Some of the sand traps are not at all in play for the modern standard course, but make perfect strategic sense if you look at the reversed course.