[SkyMarshal]

> What do I ever need distributed, cryptographic consensus for? The use-case escapes me completely,

Generally the use case for decentralized systems is if you want to disintermediate an existing middle-man who has proven untrustworthy, expensive, or problematic in some way. Or, you want to enable a group of parties to coordinate their activities in ways not previously possible without a (currently non-existing) trusted intermediary. The middle-man function is automated and federated. That’s it.

Any business model dependent on a middle-man is potentially a business model for decentralized systems, if the economics, risks and feature requirements compare favorably. Bitcoin addressed arguably the most impactful one - money - but there may be others.

>this even seems more useless than Ethereum, where I can see at least some applications thanks to the blockchain.

DFINITY is a “blockchain” in the general meaning of the word, aka a public decentralized computing platform with a native currency and attendent economic incentives. It may use other data structures under the hood than most current blockchains, but the use cases are mostly the same as Ethereum.