I had the same question; then figured I would ask when I picked up my permit; as to what the expected #'s were at a campground; to help decide if I wanted to stay on planned Itinery or change a camp site due to volume at the other site.
I wouldn't be suprised if they are asking for what our itinery is; so they can gather stats on usage; since there is no staff to do head counts at sites every day.
Trail Camp and Outpost Camp have less than postive nicknames for a reason. As the season goes along and the # of campers/wag bags and smells increase; people will spread out. In order to be proactive on how to handle that expansion and impact to the area- asking about other options- i.e; Lone Pine and Consultation Lakes; will provide some data to help the Forest Service see how they can manage the impact.
Grand Canyon limits use of areas by asking for very specific itineraries;expecting permittees to follow their plan, and if found off the planned itinery- you better have a good reason; or you'll get an additional expense to your trip.
Popularity brings damage- which in turn brings regulation to save the land from the humans.