This assumes that all programming in analogous to 'graphic design'. This analogy breaks the moment you consider that perhaps at least some programming is more analogous to, say, civil engineering or in-house material science research or in-house statistics... none of these other professionals are going to be able to disclose their 'portfolio' in any meaningful way.

Yet, mysteriously, civil engineers, material scientists and statisticians somehow keep being hired and the work keeps getting done. Baffling, I know.