Tim Lee offers a thoughtful reply. Here's part of his conclusion:
Well worth reading in full.
Libertarianism, then, isn’t a fantasy about a government that’s magically free of the corruption of concentrated interests. Rather, it’s about finding institutional arrangements in which the powers of government are constrained by clear rules limiting the damage they can do. It’s certainly unlikely that we’ll resurrect the strictly limited federal government of the 19th century. But there’s nothing crazy about seeking new limitations on government power that work in ways analogous to the constitutional and jurisprudential limits of the 19th century.