Of course, if the left had any money and any semblance of organisation, they would probably doing exactly the same thing to the Democrats.
But they don't, so the point is moot.
Both things are true. But, mostly in response to the post about them being loons, the fact is, if the Democratic Party had shifted to the left as much as the Republicans have shifted to the right over the past few years, and yet still forces on the hardline, anti-compromise wing of the left were attacking the leadership for their supposed moderation, I'd be prepared to bet good money on there being calls for 'more more more' from the majority of posters questioning the mental stability of this wing of the Republicans at present. You see, I don't really believe that this is an argument about providing good government. I'm convinced that the majority of left-wingers would support a government shutdown (or some similarly disruptive event) if it was conducive to advancing their interests at the expense of the enemy. The right, as we can see, is clearly not opposed to this (I, for one, am not, although I do think the battles need to be chosen a lot more carefully without the use of the blunt and frankly dangerous instrument that is the government shutdown). But, my point basically boils down to the fact that the left can get off its high-horse of smug-superiority over the 'loons' on the hard-right, as they know perfectly well that, deep-down, they would be doing the same should the circumstances be reversed.
Now of course, this is a hypothetical situation, and I myself am generally not a fan of being presented with overly-complex hypothetical analogies. So feel free to ignore the above ramblings.
