Ask yourself this question, would your own government use a high-level detonation for EMP to prep an urban area for assault during a major incident?

There actually is a protocol for this and yes, they would. The reasoning behind it is that it allows for absolute communications and movement disruption. It allows them to move freely without facing heavily organized opposition.

Cell phones, radios, radio stations, TV stations, almost all vehicles would cease to work, not to mention the power grid.