There is just the simple fact that such an "EMP" attack without a nuclear attack would still be an act of total war, with many people in any developed nation be

There is just the simple fact that such an "EMP" attack without a nuclear attack would still be an act of total war, with many people in any developed nation being killed if it worked. If you're willing to do that, and you have this technology... why not be willing to just bomb, or nuke? It's not like cities won't burn either way, and nukes (as you and others have stated) would do more damage. The only reason these preppers focus on it, is because it's one of the few extreme scenarios they can imagine which they could reasonably survive. A nuclear holocaust isn't something you prepare for, it's something that you hope to either avoid, or be in the hypocenter of. Some kind of mythical "infrastructure killer" that doesn't actually physically alter that infrastructure too much... that you can imagine yourself seeing the other side of I think.