It's not wasting energy, it's consuming previously wasted energy. In fact it puts a floor under energy prices so that it rather than wasting energy that you can't get to consumers you can instead use it to mine bitcoin.
Yeah, the only people that seem to criticise the 12" macbook are people who've never owned one. I still have my 2016 12" m5 and it is a fantastic little machine for people that need to be mobile.
In fact the other reason I got it was that the rest of the line (in Sept 2016) was not appealing at all. I had been set on a maxed out 13" pro, but hated the touchbar. I thought of the 12" as a stopgap until Apple realised the error of their ways.. turned out I would be waiting half a decade.