I've always thought of horseshoe theory as Moderate Hero propaganda rather than libertarian propaganda; at least that was the context in which I first heard it. Certainly one can make the case, and I would agree with said case, that hardcore libertarianism would devolve into the same sort of oppression that one sees in dictatorial Marxist and fascist societies.
Anyway, I
want to think it's bunkum, and I'm well aware that it elides a whole lot of very important differences between the extreme left and the extreme right, but then I see some of our resident leftists post things such as:
and
yes, absolutely, I'd love to see such a self-confident left faction with this type of power and determination to use it. such is why I have a hard time condemning the actions of the Cruzists from a purely bourgeois-moralistic ("you're holding the country hostage!") POV.
...and, well, it becomes harder for me to dismiss it out of hand.
(ETA: Also, cogendism. How could I forget?)