I mean, if one party pushes for use of blockchain, you'd just need to trust that specific system (algorithm, network..) and not explicitly the party pushing for it.

I also wouldn't call it power 'waste' since it does useful work - confirmation. It may be more inefficient compared to a centralized authority though. There are other ways of doing confirmations than proof-of-work as well, though each have their own drawbacks - just like a centralized system does,