&gt;  now you have a datastore where the current state relies on an ever-growing stack of immutable changesets. This sounds exactly like<p>A ledger! A concept which goes back to at least the Sumerians, and can now be efficiently implemented with a variety of technologies - databases, version-control systems, log-structured messaging systems, even good old fashioned files.<p>&gt; what we talk about when we talk about blockchains.<p>Er, no. A blockchain is specifically a ledger where the entries are certified by a distributed proof-of-work mechanism. A blockchain is useful where the parties contributing to the ledger don&#x27;t trust each other, have no way to establish trust with each other, have no trusted intermediary, but are willing to found trust on the cost of computation.<p>That isn&#x27;t the situation that the financial industry is in - there, it is a lot of existing trust, it is fairly easy to establish trust, there are plenty of trusted intermediaries, and the amounts involved mean that founding trust on computation would be astronomically expensive. A blockchain would be a really bad fit here.