The goal of a spoon is to make soup eatable. The goal of a blockchain is not to burn through a shit ton of electricity. Therefore I'd argue that your points a and b are mostly side effects, and not even side effects of blockchains. If you run high quality computer games on your system you will also burn through a shit ton of electricity. If you go to another unregulated market you also get a lot of scams and get-rich-quick schemes. Blockchains not even necessitate crypto coins, they can live without it. If you for instance like Kafka but don't like that it's centralized, you could run it on a blockchain as well.
PS: I'd argue that, depending on the type of gun you use, eating soup with a gun is still easier than eating completely without any tools. And does having a spoon really makes you worse at soccer? I'm not sure the intial thesis holds. A tool can make X easier and not make Y harder.