We humans (we assume a human is reading this book and not some form of AI, though, who knows nowadays) are good at many intricate, complex tasks; but, we're also terrible at many mundane ones. That's why we invented computers—with the software to drive them!
Well. We're not really great at spotting details buried deep inside C (or assembly) code—memory bugs are a prime example of cases where we humans can use help. So, guess what: we've invented software tools to help us—they do the mundane, boring job of instrumenting and checking millions and billions of lines of our code and binaries, and are getting really effective at catching our bugs. Of course, when all is said and done, the best tool is still your brain, but nevertheless one might well ask: Who and what will debug the tools that one uses for debugging...