that's more of a side-effect than a feature. of course, bitcoin has flaws and the energy cost of operating it is one of them. don't forget that bitcoin is one of the first large-scale decentralized currency systems. its going to have major flaws, but it does show that such a thing is not only feasible, but useful.
i am of the opinion that global consensus creates unnecessary overhead, but *some system* like PoW or PoS is needed for trustless transaction. in a local context, producer credits are an interesting approach that some folks over on ssb have been trying out.
https://viewer.sunshinegardens.org/%256mByr6BrJflzFM5gCQj5tAwDcYNgiFeZMR41LGj4PzE%3D.sha256
https://viewer.sunshinegardens.org/%25b%2FUUNV5VgLLxyt%2ByDMKomLqYIdSF4rMJBVRXO3GPFjQ%3D.sha256
https://paulgrignon.netfirms.com/MoneyasDebt/MAD2014/solution8.htm
(some of the messages in these threads are not available on web, you'll need to install an ssb client to read them)
Except that PoWs (and thus PoS) are not #trustless.
You trust each member of the grid to not invest overwhelming computing power to subvert the #blockchain.
In a local community where everybody knows and trust each other, this might work.
On a larger scale, it won't.
"trustless" isn't a good term for it, i agree. i think its more accurate to say "diffuse trust" because you don't need to trust any individual network node, but you do need to trust that the network as a whole maintains the security properties that are needed for the system to function.
A chain is only as strong as the weakest of its link.
So ultimately this "diffused trust" is just trusting the worst miner in the system.
The difference between a blockchain and a centralized database is that in the latter you somewhat know who you are trusting and they know they are accountable to you.
Now again, if you really trust each member of the system, the #blockchain can work for you.
But the "usefulness" of it decrease quadratically as the number of nodes increase: indeed it's only useful if and until each member of the community that run and use it trust every other member.
And a new member must deserve the trust of each other before being permitted to join the system.
And such trust must be very stable over time.
