To be fair: the source of this discussion was a verifiably distortionist graph produced by a very mainstream libertarian think tank. To my mind, you're simply arguing the converse fallacy. The fact that there are smart people who hold any given opinion doesn't mean that the group associated with that opinion is worthy of praise.
Basically: Hayek being "right" about something doesn't make the Cato institute "not true libertarians".
It's not just about being worthy of praise. I am just making the point that "libertarian" is a too generic term to put everything and everyone in a single bag. There are anarcho-libertarians, libertarians who support the idea of a balance between government and private investment, and many other variations.
I think the only generic you can say about libertarians is that : they care about freedom of property and consider government intervention in private affairs with criticism. Beyond this point, the commonalities disappear, and there is a wider range of opinions among libertarians than in any other political group out there. There is no real "dogma", while Von Mises and Hayek are more or less recognized as Thought leaders for some of them.
I did not claim, by the way, that Hayek was "right" about anything, I just wanted to show one of the figureheads of some parts of the movement. Getting a Nobel Prize does not mean anything to me, and I personally feel very strongly that the recent Economy Nobel Prize Jo Stiglitz does not know what he is talking about (he's just an old school Keynesian, and even Keynes himsel admitted in being wrong later in his life). Stiglitz has a clear political agenda that has nothing to do with actual economic sense.
Basically: Hayek being "right" about something doesn't make the Cato institute "not true libertarians".