In blockchain cases often there is a reference to a source of truth, something that can not be tampered with. While it is true that in a secure chain, the ledger can not be tampered with, as long as the actors putting information into the system can not be trusted, the ledger can hardly be said to contain the truth.
This to me is the classical ‘Oracle Problem’, or more commonly known as ‘Garbage in, is garbage out’ concept. Malicious sensors is not something the blockchain can solve. In energy, if the smart meters can not be trusted, you have a metering issue, not a database issue.
In use cases where everything is digital and there is no physical component in the chain, this is not an issue. Bitcoin, in-game items, as long as there is nothing ‘real’ involved.
To help the discussion forward I find it helpful to reframe the blockchain not as a source of truth perse, but more as a series of claims being logged. On this time, that specific actor/metered claims to have registered this.
Compare it to how you plan a meeting, or appointment. You will agree to meet a a location on a specific time. There is nothing final in there, just the expressed claim to be there.