There Are Honest Libertarians -- Right?

On assignment from political theory class, I've been reading David Boaz's Libertarianism: A Primer. Boaz is the Executive VP of CATO and the sort of guy who finds an idea and crams the world into it. Since I've had to follow him along in his quest to make every historical occurrence, mistake and misstep an argument for free markets and weak states, I figure the least I can do is is highlight some of the stranger parts. So here are my favorite two from the first chapter, which is about why Libertarianism is just about the sweetest thing ever:

First, we are not as prosperous as we could be. If our economy were growing at the rate it grew from 1943 to 1973, our GDP would be 40 percent larger than it is.

In case you're curious, 1943-1977 encompasses the end of FDR's presidency, Harry Truman, Dwight Eisenhower, John F. Kennedy, Lyndon B. Johnson, and Richard Nixon. So if our economy were growing at the rate it did during liberalism's renaissance, this country would be better off.

I'm genuinely confused, actually, as to how Boaz thought reference to the days of the New Deal, the GI Bill, the WW II build-up, and Keynesian economics would help the case for libertarianism, but I guess he figured no one would notice and they'd just assume the slowdown since came thanks to big government. That, of course, is insane -- In 1973, the year Boaz stops our growth at, OPEC caused a massive oil crisis, quadrupling the price per barrel of our economy's fuel. In response, Carter deregulated, then came Reagan, the closest thing we've had to libertarian, and then Bush 41, and then a roaring economy under a Democrat. Boaz is either the worst or most disingenuous historian I've ever read. That he tries to blame all this on a larger and more complicated tax code is either laughably cynical or remarkably insane.

Great Britain, which had higher taxes and more socialism than the United States, suffered even more. It was the richest country in the world in the nineteenth century, but by the 1970's its economic stagnation and national malaise were known worldwide as the "British disease".

Boaz has now managed to track Britain's trajectory from preeminent world power to underperforming economy without managing to mention the end of imperialism, World War I, or World War II. Bravo, good sir, a virtuoso performance indeed!