A couple of years ago, I read an excellent scholarly book - alas, I now can't locate the title - that surveyed conspiracy thinking throughout American history and was fairly sympathetic to the conspiracists. The author's point was that, IN EVERY CASE, there had in fact been incompetence, malfeasance and cover-up on the part of the supposed conspirators. IN EVERY CASE, however, the conspiracy theories that arose had NOTHING TO DO with the actual incompetence, malfeasance and cover-up. In other words, the supposed conspirators were simply typical bumbling bureaucrats who really had only themselves to blame for the wild conspiracy theories that arose out of their incompetence and malfeasance and efforts to cover up.
Insofar as the JFKA is concerned, the CIA, FBI, SS and DPD all had egg on their faces. All were engaged in CYA scrambling. This was the real cover-up; not a cover-up of their involvement in the JFKA but of their incompetence and malfeasance in failing to identify Oswald as a potential threat. The notion that they were "monitoring every move" of Oswald is precisely what the book describes as occurring with other historical events that gave rise to conspiracy theories: i.e., the notion isn't irrational, but it is 180 degrees off-base.