Even with immense effort at forecasting, almost every electricity industry in the world experiences long oscillations between overcapacity and undercapacity. A system just can’t respond to short-term changes when it has long-term delays. That’s why a massive central-planning system, such as the Soviet Union or General Motors, necessarily functions poorly.
It's not just the delay though but also the processing power requirements in the center are much higher if little processing of information happens at the edges. Even if there would be no delay, theres no way for one person or committee to keep in its head the problems from all parts of e.g. a country.
