I ran such a power plant with the new pollution control requirements the EPA demanded, and we still had to shut the plant down because the additional equipment permanently increased production costs. Made it very difficult to profit, even though we served the metro NYC area.
This was all before the EPA had a chance to hit us again with even more environmental restrictions and requirements that were coming before Trump was elected.
We're not talking about just blue collar people here. A lot of people making 6 figure salaries lost their jobs over these policies, myself included.
No good reason to close the plants. They were/are being built in China/India and using some of the equipment, probably, from the shuttered plants.