“Why would these people be dropped in by parachute to operate incognito to the population.”
The explanation is, this is an exercise to be used in unfriendly countries so our special forces would be parachuted in away from people and other types of transportation where they could be “spotted”.
If this is purely a military exercise practicing infiltration techniques, then the objective must NOT be to place these forces in our communities incognito. In underdeveloped countries, it might be possible for our troops in native dress to wander into town on foot. In the US, wandering in on foot in quantity would be noticed.