And I think, Blockchains don't solve the oracle problem, though. Sure, you can put anything on a ledger, but that doesn't mean it's a good idea, or that it'll mean anything real. If you run an independent and unregulated stock exchange on a blockchain, you still need to trust that the shares and the companies themselves actually exist in the first place. So it ends up being a more complicated way of doing what databases already do today.

The only thing in the real world that a blockchain can help verify without trust is work, as long as each block can only be found by hashing the answer to a cryptographic function. This is why cryptographic proof of work is the real innovation of Bitcoin, and why trying to put anything else on a blockchain is like using horses to pull an automobile.