I agree that it's important, but I'd point out that "local" means location is very important, and if you're building some new expansionist entity, that's going to be a problem. In general, getting low-tech will still require transportation (I'm not calling it 'trade').
And oligarchs aren't the only problem, there's also climate mayhem. Every community needs to have friends elsewhere for when it's time to evacuate or even migrate, and the capacity the same for others.
Without the adaptation and related capacity, localism just means waiting for a disaster to wipe the community out entirely like Pompeii being consumed by a volcano eruption.
LE: typos