At least government secrets sooner or later usually wind up leaked. Non-communication, a general tendency to hoard power and overall imperfection aren’t attributable to one particular system; rather, they can be put down to what the Tory Lord De Mauley once alarmingly referred to as “the involvement of humans”. To fear the all-encroaching state but not the negative potential of other forms of organisation seems irrational.

Precisely. Part of the problem is the hi-jacking of the term "libertarian" to mean "anti-government" (which, as with so many incorrect uses of political labels, seems to have its origins in the USA) whereas libertarians, strictly speaking, should be against any kind of power structure that can impose its will on the individual.