One of the hallmarks of the militia movement of the 1990s was the way it inspired violence: by essentially loosing the moorings of their followers from reality by promulgating a toxic brew of conspiracy theories, right-wing historical revisionism, and a bevy of false "facts" and claims against government officials and liberals generally. Chief among these, of course, was the belief that Bill Clinton and the New World Order were coming to take their guns away -- which, of course, he never did, though he did manage to pass an assault-weapons ban.
So when we point out the toxic effects of the revival of this kind of irresponsible rhetoric, it's because there's a real history behind it. It's not mere presupposition to point out that fearmongering that promotes palpably false and distorted claims often brings violent results; we already are too familiar with this causal relationship from experience.
The difference between the 1990s and now? When I was hearing talk like this then, it was coming out of the mouths of the Bo Gritzes and John Trochmanns -- the leaders and fanatical ideologues who drove the militia movement.
Now, it's coming out of the mouths of people with mainstream media programs: Glenn Beck, Bill O'Reilly, Lou Dobbs, Michael Savage, Ann Coulter.
Media Matters has compiled a video documenting how rabidly the "Obama wants to grab our guns" meme has been broadcast to the True Believers of the American Right including Beck -- who reiterated his belief the Monday after the Pittsburgh shootings: