Hmmm....
I've had more experienced instructors try to show me how much more knowledge they had than I do...not difficult, since I have the world's worst memory. I could have answered deano14s question when I was doing my CPL exams, but not now. And yes, ultimately I suppose all knowledge could be useful for students.
OHOH, I've had a 10,000 hour instructor who doesn't need to prove how great he is give me advice on better ways to teach hovering, how to give students confidence that it IS possible when they're at the point that they know they'll never hover in a million years. Or various ways students might kill you that you hadn't thought of, and what to do about it.
And I know which kind of CFI I'd rather have imparting his knowledge to me on a rainy non-flying day.