About 15 years ago a large transformer (half-million-volt stepdown) that blew up in Phoenix (in the summertime).
The nearest replacement was somewhere in the Pacific Northwest.
To get it to Phoenix, it had to be transported by barge to Los Angeles, then by heavy-lift truck to Phoenix.
The whole process took several weeks.
As I recall, there weren’t any blackouts, but the possibility was there.
Now imagine:
#1 -no power for communication (landline/ cellphone) to determine that there is a need for a transformer.
#2 -no gas or diesel since there was no power for the pumps for ships to load into bunker tanks.
#3 - no power for gas or diesel pumps for trucking
There you have it in a nutshell: No power = CHAOS !