Think of the SSNS like your inner ear drum. Does not do a whole lot upon first glance, but when somebody clocks you upside the head, your balance goes in the shitter.
Same thing. Feedback. If the flow of information from your muscles and nerves gets interrupted, due to injury or simple fatiuge, your skill goes in the toilet, as your bodies ability to compensate for simple things that you do not need to focus on is comprosmised. Most people do not give much thought to just standing there, but this takes a certain amount of work on behalf of your body and its systems.
And B-fold, it is not just my age, it is my injuries. I can lift because barbells are designed to be lifted. However, if I tried to do all that juggling trees and throwing small cars, with all of the replacement parts I have, it would look like I shit an erector set.