They always seem to stumble on purity-test questions. Extreme libertarianism would mean tons of completely absurd things being legal. Since it's kind of a pointless "party" in todays political climate, you mostly get people who are on the extreme end as a part of it without any moderation that real-life parties have to have (to some degree).
The problem is they would have to agree on that one issue. The philosophy does not lend itself well to any kind of organization.
this is a good question. I've always wondered why libertarianism wasn't more popular. Democrats wants freedom in personal lives. and Rebuplicans favor free business. Libertarianism combines both of those nicely.
When I debate libertarians I've always felt that it has never been really realistic and I think a lot of people feel that way.
I'm not American but as far as I understand Democrats type of freedom is very different from libertarians.
I have observed a strong comorbidity between “describing oneself as a Libertarian” and “being kind of a jerk who refuses to believe that any of their ability to pull themselves up by their own bootstraps comes from their unacknowledged privilege”. Perhaps this is why it is not popular.