A blackout is not just "someone shutting off your lights". It means the grid is down. And to bring the grid back up, there is a lot of effort (and energy use). If you're lucky the part of the grid with problems is just separated from the rest, but if you get 2-3 zones separated, you might end up with islands and then it will take hours and maybe days to bring it back up. Bringing up the grid from a blackout might not be possible/hard with a majority renewable power in the grid - the power source is just not reliable enough, for example the wind might stop blowing when you need the power to connect with the neighbouring region and obtain frequency sync.