Because the power lines would be cut en masse, and when they were more transformers than there are extant replacements for would blow.
Have you really reached the age you have and never even contemplated how fragile the electric infrastructure is?
The damage will not be permanent. The blue areas have engineers too and they can get electric power generation going, Freepers are very static thinkers they think well if we do that then that is the way it is forever. Civil Wars a are fluid affairs and dynamic in every respect.