Re-imagination vs realization
Society can't be re-imagined from the center; it can't be changed from the fringe.
Fringe political parties and religious movements both occupy the same social space in America, that of radical re-imagining, and both are internally divided, split at the heart, over the desire to remain pure and true to the imagined, and the desire to realize that re-imagination in society.
This was true for the Communist Party USA, perhaps in a more important way than whatever external pressures it faced, as was apparently aptly explained in Supreme Court nominee Elena Kagan's 1981 thesis, and also in Pentecostalism, Seventh Day Adventism and Mormonism, and also in libertarianism, as was seen when the newly-elected Rand Paul spectacularly failed to negotiate that gap, repeating what is a standard point in the libertarian's re-conception of America1 in the context of a non-theoretical, world-as-it-is conversation.
Libertarians are kind of famous for not knowing how to negotiate this split, for being completly deaf to how wild and wrong and horrible their ideas sound to the center they would (should) want as allies. Many take recourse to criticism, which is a way they can tentatively engage without compromising their conception, but any actual change requires the application of solutions, which is messy.
Unless it's dues ex machina, change requires a process, and process isn't ideological, isn't theoretical. It's messy, while the re-imagining is clean. I admire those who create a system of ideology -- who, can, in their minds, sweep us clean and start over -- but that doesn't mean I don't oppose them in practical terms.
1 One of the best counter arguments to this point about a "free" market response to institutionalized racial segregation, which also works as a basic explanation of why libertarians fails, can be found in Charles Lane's "On Civil Rights, no cheers for Rand Paul."