It really wouldn’t do that much damage. OK you fry all the computer chips in a couple of blocks and then... some car crashes, stuck elevators, suppose it gets kind of bad if there’s a hospital in that range, certainly business are inconvenienced. But really a half way decent regular bomb would do almost as much damage, plus all the blood and guts that terrorists love so much.
Suppose a terrorist parks his EMP near the system operations center for the electric grid for NYC or some other large city.
The grid goes down and is likely to stay that way for a while.