The weakest link principle is a way to protect critical elements of a system, by exposing parts that are here to receive the potential damage. An example is car bumpers.
I have a nice pair of earphones that I use a lot. Since my music player is always in the front pocket of my blue jeans, the other day the cable finally broke at the jack level, due to excessive and hard to avoid friction on the pocket border. Upset, I grumbled and packed everything. Could my pricey earphones be dead just because of a damaged connector?
At the end of the day I remembered the cable was in fact in two parts. The main part of the cable, welded to the expensive earphones, was actually intact! All I needed to do was to replace the lower part (the weakest link), which cost me about 1 euro.
