Like any other "ism", Libertarianism works well at its optimum in a vacuum.
Unfortunately, human beings thrive and dive in a real, fallen world.
Anarcho-libertarians like Murray Rothbard have contributed immensely to our proper understanding of the manner in which banks function. There recommendations on how society "should" work, however, border on the left-wing of the political spectrum.
Libertarians would like to see the demise of all government coercion. Yet men are not angels, and in many cases they have to be kept in line with the rule of law. The fallen nature of man does not permit public service to run primarily as private enterprise.
Human beings in general do not seek liberty -- they want security. Therefore, when faced with the shocking, the intimidating, or the unknown, men and women will give up their freedom and take what safety they can find in the hands of those who demonstrate greater power.
Above all, libertarianism does not free man from his greatest fear: death. Conservatism recognizes that freedom is a delicate and short-lived reality of a fallen world, one in which human beings will glibly sacrifice it in order to lord power over someone or be taken care of.
Libertarians who do not respect the culture of mankind or the fallen nature of human beings will always fail to command respect in the political arena. Open trade, free markets, and limited government must be created over time, persuading all elements of society to consider that a little more freedom, although initially intimidating, in the long term promotes the greatest good for everyone.