This is where the conversation gets tricky, though. If, as the bit rot example would imply, blockchain is just a fancy word for hash chain, then that statement

This is where the conversation gets tricky, though. If, as the bit rot example would imply, blockchain is just a fancy word for hash chain, then that statement is uncontroversial. Hash chains their cousins have been around for something like half a century and are well established. That's really hard to reconcile with the "blockchain is revolutionary" meme, though. I think you've got to include distributed consensus and proof of work in the definition in order to get one that characterizes blockchain as a new invention and not just marketerspeak. Unfortunately, that definition doesn't jibe very well with the usual lists of successful uses of blockchain outside of cryptocurrency, such as corporate supply chain management, because they tend to be using blockchain where a hash chain would work just as well. Perhaps they're actually using hash chains, and just using the word "blockchain" as marketerspeak. I don't have inside knowledge and couldn't evaluate such things, but it wouldn't surprise me at all if the more commonly touted examples were doing so because distributed consensus is not a desirable thing for the problem they're trying to solve. In the abstract, the problem is that it gets really hard to understand what everyone is actually talking about when the conversation centers on a popular buzzword.