Two different words are being used here, but they are not interchangeable. The words are mentor and advisor. You are correct in that the Ph.D. is supposed to

Two different words are being used here, but they are not interchangeable. The words are mentor and advisor. You are correct in that the Ph.D. is supposed to be capable of original research. An advisor who is a mentor is one to takes the raw talent of a beginning candidate and grows it into an independent researcher. Don't underestimate your importance here.