Another plausible use of the blockchain is that if you want to make a public, unalterable, undeleteable signed statement, you can "publish" it to the block chain — thinking of the distributed ledger as more like a diary than a way to buy and sell. In theory you could use this for recording vote tallies, verifying the origin of diamonds or brand-name gear, verifying people's identity, resolving the ownership of domain names, keeping items in escrow, disclosing provisional patents under seal, notarizing documents and so on.

Without diving too thoroughly into the details of each of these, it seems the use cases all fall apart pretty quickly. For voting, the status quo is recording the total number of ballots cast, with the voter dropping a visible paper ballot in a box, and journalists and observers from both sides watching the ballot boxes the whole time. The tough problem in voting is keeping who voted for who anonymous and yet making sure that voters and votes are one to one. Paper does this so much better than blockchain.

For a public notary or similar, verifying your driver's license or having witnesses known to you present means that it wasn't signed with a stolen password or private key — but, if a password or private key is adequate, you can just publish it signed with a PGP key. For establishing the authenticity of brand name goods like watches or handbags, or that a diamond was ethically mined, the ledger being distributed and encrypted doesn't add any value — the originating company can just include a certificate you can verify online, just as they have done in the past. In cases of escrow, a smart contract can automatically pay for the goods without a need for a third party to verify and hold the funds, but you still need a trusted party to verify that the goods are delivered and as-promised.

And finally, if you want to irrefutably prove that you knew X at time Y without disclosing the actual knowledge publicly, encrypt it and email it to yourself at both a gmail and a hotmail address or post it on bitbucket, or print it out and notarize it, or postmark it by mailing it to yourself, or tweet an md5 of it, or whatever. But then again, how large is the irrefutably-prove-you-knew-X-at-time-Y-without-disclosing-X industry? Can you think of any leading company, or any company at all, that provides this service?

For domain resolution — the process of figuring out whose servers get to see the traffic and respond to your requests when you type a URL into your address bar — it's promising to imagine that an all-digital record of smart contracts, where the actual act of payment being published to the ledger also updates who the domain resolves to, obviating the need for domain escrow services. Yet in practice, as with the DAO or other smart contracts, if valuable domains change hands due to theft or security issues, you actually need a way to override the ledger — as the result of a court order, for example. Just like with government-backed, law-backed bank accounts, real companies won't prefer a situation in which a security breach or stolen password could result in someone else permanently and irrevocably owning bankofamerica.com or disney.com or sony.com or whatever. Adopting block chain technology makes theft or impersonation more likely rather than less. It sounds hypothetical until you realize more leading bitcoin exchanges have been hacked than not — something that very rarely happens with the leading domain name providers.