>> For all intents and purposes we have lost the 1800s technology of community barn raising. At least we as defined as HN participants.

I am pretty sure 'we' havent (in the sense 'we' = sum of HN member knowledge).

HN includes some pretty amazing members: http://jacquesmattheij.com/how-to-build-a-windmill

I don't have links handy, but HN includes people who homestead, and practice many mostly-lost arts.