It all depends why you're having lessons, what you want to learn, and what the teacher is purporting to teach. Condemning an unknown and quite possibly imaginary guitar teacher for simplifying harmony to someone who may well be just wanting to learn a few chords to sing to is just silly, though it's drawn out some interesting views, which I hope was the purpose. However, everyone except the alleged teacher dangling in the noose seems to be in agreement on the existence and nature of B#, and we're not really sure about him. Different approaches to teaching and learning music yield different results, and that's what music needs, not a bunch of robots all trying to conform to the same sterilised standards. The proof of the pudding..

For interest's sake: It's been long since shown (ref. my link above) that the brain can detect far finer fluctuations of tone, pitch, tempo, etc. than any performer/the human body can consciously control.