Not sure what hierarchy you're referring to, but I'll assume government, then talk about why everyone seems so extreme. and where moderateness comes into play.
The desire for smaller government (or larger) is neither left or right wing exclusive. If you think of it as a political compass (though it shouldn't be permanently applied in such a manner as there are multiple categories of policy surrounding government) Authoritarianism (hierarchy) is the north and anarchy or lack of government is the absence of such a hierarchy. Most leftists find themselves mid-left and somewhere mid anarchy, which isn't to say they are anarchists or just straight leftists.
It simply means they are of center, to the left. This means that foor every left policy they have, there is a number (however small) of right wing policies that they embrace. The application and labeling the left as the "Radical Left" is complete and utter bullshit. By this definition, I mean it's patently false. The illusion of Leftist radicalism stems from the the authoritarian tendencies of the right which creates a greater distance between the left and the right to be essentially the hypotenuse of a right angle triangle.
Assume you're on -5x left, and -5y anarchy.(-5,-5) and your right wing counterpart is (5,5) (positive) (A^2*B^2=C^2) Since we have a difference of 10 on x, and a difference of 10 on Y, that means the justified distance is 14,142y. However, since we are diametrically opposed in the vertical and horizontal scales, we seem super extremist to each other, even though the majority of everyone involved in the discussion are moderate within their own field.
Centrists, in the literal sense of policies they identify with, in my experience and observations, are a dying breed. A lot of people like to claim centrist, but because of the polarization due to culture wars, the line is pretty extreme to be center on these days.