Traditional map folding allows you to reference a portion of the map without unfolding it entirely. When I realized this, I stopped hating the map folders.
Actually, the same professor (Miura) who invented the fold I talked about in that note came up with another way of folding (that also involves binding part of the map) that does "reference a portion" much better than the traditional way manages. You can find it if you google for "Design of portable maps enabling longitudinal access" Miura, 2006
That looks cool but actually sucks for map's because it does not handle edge transitions well. The according method which most maps use is designed so you can open a reasonably arbitrary section of map at the same time which is important when you want to do things like compare routes which cover 4 folds at the same time. All the while being able to quickly flip it over and see what's on the other side.