What every programmer should know in this context is a euphemism for how Drepper views that set of things to know i.e. Yes it's hard and yes really should know,

What every programmer should know in this context is a euphemism for how Drepper views that set of things to know i.e. Yes it's hard and yes really should know, you're a professional programmer. Storage is a little bit further away than memory, but it's still very important in certain lines of work