Ok - Ill try -
Picture this, with no servo saver, there is nothing in between the steering linkage and the servo to give out in the event of abrupt impact. Thus, all force would be transferred directly to the internal components of the servo. Stripped gears etc..
The servo saver is spring loaded and can absorb a good amount of shock. A good example would be if you ran wide open throttle into a pole with your front right tire, the force would travel all the way to the servo saver and be absorbed their as opposed to the servo.
Did I explain it good enough?
Hope this helps and didnt confuse you.