I agree with STLHDR1, especially side drifting, the guides rod is important for feedback that everything is working right and it also helps give the client an immediate rod after a break off on a snag. It can be a big challenge to fish, retie, and run the boat on the guides part. You can also consider him fishing actually an instructional demonstration also.
Another type of fishing where it is important is trolling spinners like in Tillamook Bay. Generally the guides tries to keep clients weight droppers just off the bottom, but the guide is always dipping the rod and checking where bottom is. The current, boat speed and wind effect the spinner depth critically (that's the secret).
Personally , I enjoy the opportunity to tell the guide that I don't want his &%$*%in' fish!