I think I now understand why it might be an advantage to have disc brakes on a fully loaded bike.
Near Salt Point there is a dirt road called Kruse Ranch Rd, which turns into paved Seaview Rd, which turns into Meyer's Grade. Halfway down the 2 mile downhill from hell I had to stop and cool my rims, but it was very difficult to stop. At the same time if I let go of my brakes I would start accelerating at an amazing rate, and I was sure I would lay it down on the tight curves. It sure was a thrill, but I don't think I'd like to do it again. Unless it was an unloaded bike, of course.
The spot where I let my brakes cool.