These are great edge cases, but certainly not the common case. I think, in general, people jump to a debugger well before they're ready to actually understand what the debugger is telling them. This turns into a random walk through the source and ends up being a pretty big waste of time, compared to actually reading and understanding what's going on.

That being said, I'm planning on using gdb this afternoon to debug an x86 (16-bit) bootloader I wrote 4 years ago. It was part of a class project, and the prof ended up using it as example code. I think there are subtle bugs in it though...