I find that my understanding of different layers is usually not needed but is rarely important toy ability to solve thorny issues or figure out ways to do things or debug issues that others are not even trying.

I'm working in areas of systems programming where such knowledge and willingness to go deeper into the stack is helpful, even if rarely so.

I can't say I understand the kernel, I only scratch the surface of most of it and only dug deeper where I really needed to and only as deep as time allowed me and the need required though.