The parent said _understanding_, not writing your own[1].
To take an example of a web startup (just because the are the most common), here are some question that require understanding the basics of operating systems:
1) "why is my database cache constantly being swapped out to disk when there's enough memory in my machine"
2) "why are the pages taking so slow to load, even though I'm only serving a few hundred hits a second"
3) "what is my webapp doing that's making python/ruby take up 100% of the cpu" (to find this out, you'd likely be using gdb, ltrace and strace which very explicitly require at least a passing familiarity with C and POSIX)
4) "why is there a process showing up in ps/top that I can't kill even with kill -9"
Finally, you certainly have to be a good programmer to start a startup: not the best one, not a "10x programmer", but a good one (irrespective of what sort of applications you write). You can't be a good one without understanding how your programs work.
[1] That said, I had my hands dirty in Linux source code when debugging an issue while working in (of all places) an email security company.
To take an example of a web startup (just because the are the most common), here are some question that require understanding the basics of operating systems:
1) "why is my database cache constantly being swapped out to disk when there's enough memory in my machine"
2) "why are the pages taking so slow to load, even though I'm only serving a few hundred hits a second"
3) "what is my webapp doing that's making python/ruby take up 100% of the cpu" (to find this out, you'd likely be using gdb, ltrace and strace which very explicitly require at least a passing familiarity with C and POSIX)
4) "why is there a process showing up in ps/top that I can't kill even with kill -9"
Finally, you certainly have to be a good programmer to start a startup: not the best one, not a "10x programmer", but a good one (irrespective of what sort of applications you write). You can't be a good one without understanding how your programs work.
[1] That said, I had my hands dirty in Linux source code when debugging an issue while working in (of all places) an email security company.