I'm not sure what you mean by "three basic closed position scales that you can play anywhere up the neck". Using 3 notes per string, there are 7 basic closed position patterns, in 12 keys (major and related modes). There are other patterns of course. Even the ones coming "out of the open G scale" number more than three. Add more for minor(s), and various other scales (pentatonic, exotic) and "playing up the neck" isn't as simple as it is made to sound.

Peace, Mooh.