They try. We try back.
So far, the laws of physics overcome such ideas.
If you are close enough to use a directed EMP type weapon you are close enough to be destroyed yourself or reach out and destroy the target using other means.
Jamming, interfering, and denial, are all part of the Cyber Warfare game.
I think you’d agree that personal and national politics are much bigger threat to prevailing against aggression than any weapon system out there.
If the power goes out, I predict we won’t know who or what did it.