You don't like it when people paint conservatives with a simplistic broad brush, but your defense here is to define all conservatives as people who hold to a single idea, libertarianism. And that's a ridiculous over-simplification of conservatism.

Even if conservatism is that monolithic, history records a powerful rebuttal to your thesis: After 9/11, conservatives stampeded into the arms of authoritarianism, shedding rights like due process and free speech and privacy as if they were clothes that had suddenly caught fire. It was conservatives who applauded the Patriot Act and the establishment of the Ministry of Homeland Security, and conservatives who responded to any concerns about massive NSA wiretaps and intrusive TSA strip-searches with a historically-tone-deaf "und vhat do you haff to hide, hmmmm?"

Where were those "people who believe centralized government authority is too powerful, and that individual and economic liberty are in danger of being suppressed"? The phrase "true colors" comes to mind...

That was one impressive example of conservatives acting in unison, albeit in direct contradiction of their supposed core belief. But you find a diverse cast of characters in the Republican "big tent", including many who exhibit that "authoritarian conservative" mindset that, history shows, is a precursor to fascism. Want to try and tell me that religious and other social conservatives aren't in awe of, and cowed by, Authority? I'd say that the libertarian economic and political theories you call the litmus test for conservatism are actually way down the list of the concerns of social conservatives. Obeying thy parents, obeying thy church, obeying thy god, obeying the rules, obeying Authority, all rank higher. And do you think people who believe a theocracy would be just peachy for America couldn't ease just one step further and embrace fascism?

The fig leaf of libertarianism isn't broad enough to cover the creationists and fundamentalists and birthers and racists and "low-information voters" who are the heart and soul of conservatism. The credibility of the sober bits is seriously undermined by the loopy bits.

I think trying to put a libertarian face on conservatism is an insult to Libertarians. Libertarians aren't at much risk of gravitating to fascism, but large segments of conservatism are.