In the past, if economists discovered an inefficiency in the market, they would say "and the government should correct this inefficiency with policy X". Public choice economists don't ask if governments should do X, but rather will they do X.
It turns out the incentives facing government actors aren't very good. They have much fewer incentives to act efficiently than market actors. It is possible to have competent officials at the head of a small bureaucracy produce good results. However, I doubt this is possible for the United States, which owns the largest bureaucracy in the world.
So, there are real reasons for limiting the scope of government.
There are plenty of good people working in the civic media area, so there's a good talent pool to draw from.
An efficient government is a laudable thing that everyone should want, and so cutting away the fat is a natural thing to do in any sort of political light.
I don't know why libertarians at large seem to claim ownership of this notion.