> It's the whole system that is either safe or not, not the individual components.

This is a core perspective disagreement. While this is true:

> If your system gets hacked by a buffer overflow in the end, nobody cares whether it was the linker that overflowed or the code emitted by the linker.

That does not mean that increasing the amount of safety in the individual components isn't helpful, because it helps minimize the above outcome, even if it will never be zero.