But the problems of a widespread long term power outage sound like something a centralized preparation could cope with at least as effectively, if not more so; partially because it can simply be prevented appropriate preparations, and partially because even when a blackout cannot be prevented you almost certainly can ensure that recovery is relatively trivial (as compared to "rebuild transformers"). Both mitigation strategies simply aren't available to hyper-local prepper style preparations. Not to mention the fact that the population (even in the low-density US of A) is probably much higher than a prepper-tech based society can ever hope to sustain. I.e: mass prepping would likely replace famine and other catastrophes with immediate civil war, followed by famine and other catastrophes.

In abstract: Decentralization offers a remedy because it is distributed; however, the best way to make a system (more) distributed may still be via a coordinated (i.e. centralized) approach.