Imagine, for a moment, what would happen if a power outage crashed the electrical grid across the enormous sprawl of a city that is the US east coast from Washington northward. Millions of computers would drop off the global network; crippling botnets, emptying chat forums, role playing servers, and choking off the flow of commerce.
Sure, backup generators would kick on all over; government, emergency, and commercial sites would stay online. Traffic online would fall drastically until residential computers powered by the electrical grid returned to operation. For millions, the "cloud" just evaporated.
Personal habits would be disrupted, the cutoff from online activities forcing alternative choices. Walking outside, the stars would be more visible without competition from billions of lights. Vehicle traffic would drop off sharply, as there would be no point in going out when most public places would be dark.