> A global financial system could very likely be built on top of a system like this.
No it can't.
Two major reasons (and this isn't an exhaustive list, just the first couple that spring to mind): 1) the lack of scalability both in transaction rate and data volumes, and 2) the lack of transaction reversibility.
I always find interesting the people that claim with certainty that technology cannot solve X when there are no known physical laws forbidding it.
Scalability is already being tackled, rollups are already scaling Ethereum today. In combination with data sharding they will allow scaling Ethereum to the order of 10 million TPS by the end of the decade. But much earlier than that we will see multiple orders of magnitude increased scalability.
Transaction reversibility is a non issue. Any trustworthy ledger is non-reversible. The way you implement a reverse transaction in a pen and paper ledger is by writing a new transaction that undoes the effect of a previous one. Not by erasing the previous one. Ethereum itself is non reversible but this exact logic can be implemented over Ethereum in your smart contract if so desired. And, in fact, there is smart contracts that operate like that. For example, USDC the stablecoin by Circle has this logic built in, it can freeze funds and take control of them at which point it can do whatever it needs, send it to law enforcement, reverse a transaction, etc... This is one of the lamest counterarguments people put forward.
No it can't.
Two major reasons (and this isn't an exhaustive list, just the first couple that spring to mind): 1) the lack of scalability both in transaction rate and data volumes, and 2) the lack of transaction reversibility.