The incentives don't match. No matter how efficient we make our power generation, PoW will simply scale up and consume more, making those gains moot. It will use up cheaper renewable energy and force everyone else to keep relying on fossil fuels. Of course I should not forget to mention the e waste which is a concern regardless of how much greenwashing is done
PoW will scale up to match, be vigilant about which sources it uses, which sources an enterpriser wants to try to use. Be vigilant about the coal plants coming online, while non-grid connected methane-reducing sources are applauded.
Large scale miners allowed this argument to get out of control because they didn't want people to know their sources of energy (extending their lead in front of other miners), and now this ESG boogeyman has taken an inaccurate life of its own.
At the end of the day, if you really think you have another economical use of energy because proof of work can't possibly be "it", then you still have to thank Proof of Work for making you notice an energy source and use case that everyone else failed to notice for decades.
I think PoW's incentives to grow are something that needs a lot of vigilance to curb, as it will be governments eventually using it in the most economical and polluting way, in order to control the network. But I think enough people can see through the "I just want any other thing to use energy waaah" argument that the private sector ban is never going to happen.
