I know of at least 2 former CFI's who quit due to the pressure from mounting regulations and paperwork req'd to operate a small one pilot school, the responsibility put on the CFI, while a student was flying a short nav ex. Partly why I never returned to instructing.
Like Sunfish I too had this idea that it was all learning and helping, but quickly learnt the opposite, exactly as he describes.
I have days when I miss being involved but then again . . .