Really? I disagree with this completely. If you're hitting any sort of depth below 80FSW, then you are affected by narcosis. Only the fool thinks they are completely immune and the fact that many don't "feel" it, shows just how insidious it is. On the other hand, your PDC never ever gets narced. It remembers the details of your dive far better than you ever will and in far greater detail. Frankly, the people who dive their PDCs in gauge mode scare the snot out of me. Why? Your brain will fail you on almost every dive and it often hides the fact that it has failed. PDCs are great until they do something so radical that you can't help but notice the flaw.
Moreover, we rely on many tools to get us back safe. Your regulator, the boat your diving off, the car you got to boat in and the list can go on.