Libertarianism gets marginalized in American politics because it doesn’t fit into the two-party paradigm.
Well, that’s one version of the underlying cause and effect. A rather more accurate one is hinted at earlier in the piece, albeit embedded in some spin:
Maybe it was inevitable that the National Opt-Out Day, when travelers were going to refuse body scans en masse, failed to become the next Woolworth’s sit-in (how do you organize a movement that abhors organization?). It turned out most Americans actually supported the body scanners. But the moment was a reminder of just how strong, not to mention loud, the libertarian streak is in American politics.
The body scanners were, in fact, an excellent example of the fact that libertarianism is marginalized in American politics because it’s a marginal, unpopular view — something that becomes particularly obvious when you consider what percentage of the minority of the people who were opposed to the body scanners supported all manner of arbitrary executive powers in service of the War On Terror (TM) so long as there was no chance that they would be personally effected. Libertarian beliefs on major issues generally range from unpopular to extremely unpopular, and this includes issues where I share libertarian beliefs. There’s really no puzzle here. Principled libertarianism would have very few adherents even it was propounded by hipper band than Rush. Another hint: the primary focus of Republican opposition to the ACA involved arguments that the government should keep its grubby paws of Medicare.