Call it terror, modern warfare, or Sponge Bog Squarepants if you wish, but annoyances such as a widespread power outage that occur frequently enough will eventually disrupt a country's economics and productivity on a large scale. Take, for another example, the threat of a mined harbor. That $100 device floating somewhere in the shipping lane (if it's even there) is designed to restrict access. Why is the US military spending many billions of dollars each year on mine countermeasures? In part, it's because your cheap explosive device is stalling millions of dollars per day on commercial traffic. A simple mine can be deployed by any country or organization. Likewise, destroying power infrastructure, oil supply lines, or communication lines can be done by anyone with the initiative. Still think a power outage is a minor inconvenience?