I think the point is that the only way to reduce crypto profitability is to impose a soft limit on electricity by massively increase the cost of electricity if you exceed a certain allotment. Otherwise, there's no real way to tell if someone is mining crypto or if they just using a lot of electricity unless it's a massive mining operation.
and who's to judge it was useless? If you're the one paying, then you can make this judgement. Otherwise, you're merely putting your own moral values above someone else's.