An excerpt is below just to whet your appetite:
So now we have the absurd situation of having ultra fit referees, but not allowing them to use that fitness, by instructing them to adopt conservative positioning. At the same time there is the tacit acknowlegment that the CR cannot see what is happening near the goal line from these positions, and so the AARs are appointed! Although the big competitions and wealthy leagues can afford to have 6 officials assigned to each match, this is way beyond the financial and manpower capabilities of most other competitions. Many are unable to provide even ARs or 4th officials as it is.A very good read, from a very smart (former FIFA) referee.