Is there actually any chaining going on, or is this a standard "trusted timestamp"? https://en.wikipedia.org/wiki/Trusted_timestamping
(It's also possible that each published hash is just a brand new hash of the aggregate, but this seems somewhat less likely based on the wording.)
ETA: Looks like it's a chain, or rather a Merkle tree. From the horse's mouth: https://news.ycombinator.com/item?id=17865168
But I think we can agree that a Merkle chain like this would be sufficient for most of the things people are trying to use blockchains for recently, which certainly says something.
- it's a distributed consensus system (often around "blocks", but e.g. iota is not)
- it's a chain of hashes to prevent mutation (around "chains")
Very (very) few things benefit from distributed consensus IMO. And not all altcoins use blocks at all. So I tend to lean towards hash-chains. Publicly-verifiable immutability is useful in quite a lot of real-world scenarios.