Never. I'm a data scientist myself and know many other so-called data scientists. But coming from an engineering background, I pretty much agree with you. & interestingly, all of the ppl I know who claim they want to write an OS one day are all data scientist. Seriously! They don't even know what's unit testing!!!
The OP is explicitly about the kind of programming work where "An entire interesting application may fit in one file.", which doesn't tend to apply to OS's nowadays.
