[donuteaters]

Actually, all of those have something strongly resembling a kernel, and DOS in particular makes a nice distinction between the basic services (BIOS) and whatever userland you choose to install on top of it. I think you're making my point - "Operating System" used to mean the "kernel" before RMS wanted to ride on Linux's coat tails and Microsoft wanted to bundle their browser anti-competitively - both of which are distasteful.