There's a much simpler explanation which I find equally plausible. If the job you're applying for doesn't require a master's degree, then why waste the reader'

There's a much simpler explanation which I find equally plausible. If the job you're applying for doesn't require a master's degree, then why waste the reader's precious attention on something irrelevant? As a programmer applying for a web development job, would you mention that you know how to program x86 assembler? Probably not. Let's not forget that the word "résumé" is French for "summary". You're not supposed to include everything!