Today, for perhaps the first time, the libertarian movement appears to have genuine political momentum on its side. An estimated 54 percent of Americans now favor extending marriage rights to gay couples. Decriminalizing marijuana has become a mainstream position...[libertarians support] the drive to reduce sentences for minor drug offenders...The appetite for foreign intervention is at low ebb...deep concern over government surveillance looms as one of the few bipartisan sentiments in Washington...It's gratifying to see so many Americans take up these causes, but that doesn't change history. All of these are liberal positions advocated by liberals for decades and decades. Crucially, liberals have fought for these positions when libertarians have been unwilling to, and often in the face of fierce opposition by libertarians. Liberals often maintained these positions at their own political expense, and it has largely been through their sacrifice and dedication that these causes even became viable.
Draper's reference to foreign intervention is just the most obvious case in point.
Consider the most significant instance of foreign intervention in modern history: the invasion of Iraq. Liberals didn't merely oppose this - they led the opposition, and it was the central rallying point of their politics throughout the GWB presidency. The Democratic party was a major vehicle of their opposition, though a glance at contemporary protests show the heavy involvement of organizations even further to the left: the A.N.S.W.E.R. coalition, United for Peace and Justice, the Green Party, and so on. Accordingly, opponents of foreign intervention were overwhelmingly associated with the left, and defended and criticized on those terms. Opponents of the Iraq War were routinely attacked as Communists, Socialists, Big-Government liberals, and even sympathizers with the notion of a totalitarian Islam Caliphate. Rather than disavow their acceptance of liberal governance, critics of the war routinely maintained that government funds being wasted in Iraq would have been much better spent on welfare programs and maintenance.
It's become a political truism that Libertarian opponents of intervention were missing-in-action during the Bush years - but really, that's far too polite. In reality Libertarians supported foreign intervention, as they often have. Not just passively, though they did that too - as when CATO repeatedly maintained radio silence on the issue to the point that even allies started criticizing them. And not just from the top down, though they did that too - as when CATO fired anti-interventionalist Charles Pena. Nope, they did it actively, and at the level of individual voters: for instance, supporting Bush against Kerry by an overwhelming 59-38 margin in 2008.
Does any of this mean that Libertarians aspire or intend intervene abroad?
Libertarians typically respond to these points by insisting that they were making pragmatic trade-offs to advance things they cared more about - supporting the Iraq War because Bush also promised tax cuts, for example. But that's not a counterpoint. Politics are about what positions you support in theory - they're about what trade-offs you actually make. You do not get to call yourself an anti-interventionist if every time the issue comes up you are willing, for whatever reason, to support intervention and oppose the people who oppose it.
This line of criticism holds across the board. There's an old joke on the left that Libertarians are just Republicans who want to smoke pot - but it's worth noting that they haven't been doing this by actually advocating legalization. For the most part, Libertarians have spent the last fifty years voting for the party that regularly uses "pot-smoking hippies" as a way to insult liberals. When they want to smoke up, they just do it, because they're privileged and they can get away with it. Sometimes, as Draper reports, they even brag about it in contests!
Ironically, the emergence of the modern Libertarian movement has mostly been an outcome of widespread acceptance of the liberal agenda. Left-wing opposition to war, discrimination and the war on drugs have been so successful that right-wing capitalists have had to accommodate to these realities. Far from representing a "purer" or "more-principled" version of Republicans, Libertarians are mostly Republicans who have capitulated to pressure from their left.
Predictably, the losers in this contest are now trying to re-write history and insist that they were the winners all along. Its the exact same revisionary move we see today among opportunistic Republicans trying to claim the legacy of the Civil Rights; their strategy may seem implausible now, but the Libertarian rebrand seemed implausible too - at first. When writers like Draper invoke these talking points without criticism, they quickly move from implausible to truism pretty fast.