Libertarians aren't a total failure. They had major ideological influence within the GOP, who used their stances to "moderate" mainstream conservative policies without changing their fundamental governing policies. So there's now a "libertarian argument for gay marriage" being parroted by people like Ben Shapiro to appease the new recruits like Dave Rubin; and the NAP is being used as a saving-face reason to back out of the War on Drugs. But they aren't going towards more limited government or dismantling the state itself; they've made
negative progress in the last few decades.
In a way, the libertarian journey on the right has mirrored that of the liberals on the left. For a while, the American left was composed of liberals and progressives, each with their own agenda but generally working together against the social, fiscal, and national conservatives groups. Then by the 2010's liberals accomplished most of their agenda (sexual liberalization, gay marriage, federal backstops for social programs) just short of drug legalization, which is slowly underway. Suddenly they had little in common with the progressive agenda, the progressives pushed through radical cultural shifts, and declared "liberals get the bullet too" when their fellow travelers balked at the extremism.
American liberals are becoming isolated in the same way libertarians were, but with less of a cohesive ideology to coalesce a party or movement around. They even tried joining up for a brief moment, before that "
liberaltarian" idea collapsed under the obvious contradictions.
(For all the lolcow behavior Sargon does, he properly recognized that liberals needed an explicit ideology to describe how they're different from modern leftists. "Liberalists" was a dumb name, but it's a necessary intellectual first step if you want to turn your collection of policy preferences into an identifiable movement.)