Ofcourse there are edge cases that don't work with a debugger. I have been there too. Timing sensitive applications like controlling the fat-TV live on scanline/pixel level can't be debugged. Physical objects that move over a certain speed can't be live debugged because of physics. This is still edge cases.
Arguably, once you are working on a sufficiently complex and mature system with good-enough tooling and tests and development practices, these edge cases can come to dominate. I don't spend time debugging simple things on their own, because the simple things on their own are generally well tested, so the failures that do happen emerge from their combination and integration into complex systems.
That said, I do spend a fair bit of time using a debugger as my first-line response to an issue - but overwhelmingly it's to examine a crashdump of the failure rather than investigate a live process.
