We decided a couple decades ago that an 'immutable ledger' would indeed be useful. And you don't have to expend tremendous amounts of time an energy creating su

We decided a couple decades ago that an 'immutable ledger' would indeed be useful. And you don't have to expend tremendous amounts of time an energy creating such a thing. See Hash Chain[1] at Wikipedia, and notice the second sentence. 1 - https://en.wikipedia.org/wiki/Hash_chain https://en.wikipedia.org/wiki/Hash_chain