LOL... we'll build them in miniature 1"x1" square to say they "exist" and we can actively NOT put anyone in them. 
Of course too, inherent in the snark here is the fallacy that Libertarianism is "pointless" because it won't be achieved 100%, as if then there's no point in at least moving as far in the direction of liberty as possible as we can get. 
I guess it shouldn't continue to surprise me, people who at least claim to support RKBA, limited government etc. immediately fall back on statism as long as it's "their kind of statism". I'm bombarded with it every day.
You're confusing a discussion of the theory underlying Libertarianism as a philosophy with the pragmatic application of it. In practice, aside from when they're being useful idiots to the left on things like immigration and redefining marriage, my interests generally coincide with that school of thought. The issue of immigration does bring up one aspect of the inherent utopianism of Libertarians: for it to really function well it needs to be holistic to work well. Implementing one aspect of it (like open borders) without other aspects (like an end to welfare etc) is disastrous. Of course I think open borders are a disaster anyway, but that's a different discussion.
Regarding "statism"... All government is enforced morality. Whether that morality be "Punish those who violate the NAP and do nothing else" or "Everyone must go to mosque and worship" isn't really relevant. So this silly hand wringing over enforcing morality and the evil statists who don't
really care about freedom gets old. Unless you're a full on anarchist/voluntarist then you're in the exact same position as the woman from the old Churchill joke: just haggling on a price.
I'm just waiting to hear what is utopian about libertarianism.
Are there going to be libertarian labor camps when we take over ? (Privatized, of course).
Already answered, but I'll add my piece. It's utopian for two primary reasons. To work (even in theory) it needs to be holistically implemented all together. And because it misunderstands human nature as well as the nature of political institutions.
Let's say you find Aladdin's lamp, and you wish for the world to have perfect Libertarian .gov in place. Setting aside foreign policy considerations for the moment, what do you think people's reactions would be? If they didn't like some aspects of it, and wanted to get those statist jackboots on and oppress the poor widdle zoophiles: how would the .gov react to this? Ignore the will of the people? Exclude them from the process and give them no means to influence the .gov? How do you think that would work?
Doctrinally pure Libertarianism is incompatible with representative government, because most people don't want what it is actually striving to achieve and they never will. Libertarianism's saving grace is that they're completely unable to actually achieve their goals, so the pragmatic, non-doctrinal applications of their philosophy can do a lot of good in influencing the existing process.
In the end, I think Libertarianism (as a philosophy, not in the colloquial way it is normal referred to) is very similar to the whole "Pick Up Artist" philosophy. Some practical applications that work very well and for the reasons stated, some practical applications that achieve the stated goal but are actively harmful to all involved long term, and some crazy nonsense that directly flows from the flawed underlying philosophy carried out to its logical conclusion.
