Electricity is not perfectly fungible because of infrastructure costs and transmission losses.
The nature of mining as a competition for the cheapest electricity means that miners will naturally move towards areas where the electricity is not in demand.
They are using electricity to do computation. Even if, hypothetically, the electricity could not be transported elsewhere (and that's not realistic), if hypothetically manufacturing could not be set up there (and that's exactly what normally happens), the electricity could be used to do computation which is _actually useful_, which is why companies set up datacenters in the middle of nowhere with cheap electricity.
The nature of mining as a competition for the cheapest electricity means that miners will naturally move towards areas where the electricity is not in demand.