Here’s a good piece from the Economist which is generally in support of my theory. They say:

What’s scary about extreme right-wing rhetoric, to a great extent, is the way it’s bound up with a legitimation of private violence as a defence of freedom. This has not always been the exclusive domain of the right. In the late 1960s and 1970s, it was extreme leftist groups such as the Black Panthers and the Weathermen whose rhetoric legitimated armed violence as a defence of “the people”. It was appropriate for cooler heads then to denounce such rhetoric as scary on its own terms, and crippling to democratic politics. That lesson was effective: even the most inaccurate and excessive rhetoric on the left these days doesn’t invoke violence. For the same reasons, today’s right should drop its habit of couching political points in violent terms.

I also note they cite to Andrew Sullivan and say:

Andrew Sullivan has been running rhetorical-excess prizes for both the right and left for years now, and he says “the simple fact of the matter is that there’s far more on the right than left.” More important, he thinks excessive rhetoric on the right routinely involves dehumanising one’s enemies and invokes the spectre of violence in a way leftist rhetoric rarely does.