Also, I think many people, Americans in particular, overestimate the ability of "market systems" (i.e. "the marketplace of ideas) to self-regulate or the desirability of the results of that self-regulation.

It's one thing to let Nazis march down the street in Illinois, where they are a small group of pariahs with no hope of power; it's quite another to let them march down a street in a place where they've had power and used it to bad ends (and can be assumed to have significant residual support).