Except they really can't. Once they go down the path, it only takes one demagogue to complete the journey. One need look no further than the Weimar.

That's hyperbole. There's absolutely a range of different viewpoints one can have on, say, balancing law and order goals vs. other societal interests - and the various countries of the world all land on different spots on that spectrum - without descending into totalitarianism. It's absolutely not the case that going one step to the right leads you inexorably to Fascist Germany, any more than taking one step to the left leads you to a Marxist-Leninist collective economy where the means of production are owned by the state.

We don't live in a world where there is only one possible correct view on how society should be structured, and everything even slightly to the right of that view is actually fascism or will unavoidably lead to fascism.