Similar myths happen after every war. It is a guilt reaction of the survivors. It should be no surprise that certain factions of the elite decide to opportunistically use the myth for their own political purposes. To describe it as simply a ruling class plot is an overly simplistic analysis that sees power exercised by mechanical wire-pulling by elites.
Having fanned the flames of the myth to aid Republicans, these elite propagandists could not easily douse the fire. The myth took on a life of its own. It fueled the rise of the militia movement.
The version of the myth spread by the Prouty/Gritz/Perot/Sheehan alliance is that the CIA and its allies are a traitorous elitist faction of the true American government--a government which should be run "by the People." Typical populist rhetoric in support of an oustider elite faction. This is the basis of the Rambo narative in which wealthy college-educated liberal elites send working-class stiffs off to die. Gibson in Warrior Dreams talks about this.
So-called "leftists" such as Sheehan and Oliver Stone have incorporated this right-wing propaganda into a simplistic anti-elite critique that shares more with fascist anti-regime narrative than a truly radical systemic/institutional discourse. I wrote about this in "Right Woos Left."
-Chip Berlet