More reliable? We are not living in a world where every roof is covered with solar panels. Our network is not a wireless mesh.
During a war power plants will get bombed. Network and power cables will get bombed. Roads, railroads and bridges will get bombed, so power plants wouldn't even get fuel.
Heck, if they wanted to be really surgical, they could just bomb the power lines entering the power plants. The effect would be total shock and aw but much easier to reconnect afterwards when they have the new puppet regime in place.
During a war power plants will get bombed. Network and power cables will get bombed. Roads, railroads and bridges will get bombed, so power plants wouldn't even get fuel.