Does blockchain without currency make any sense? I keep reading about private companies building blockchains for stuff like supply chain management, and about the billions of dollars that are going to be invested in blockchain over the next 5 years, but there is a gap in the logic here that I don't get.
Distributed Ledger Technology is totally reliant on participation to establish the principle of Distributed Trust. If there are not enough independent actors in the network, you cannot rely on the immutability of the ledger.
In Bitcoin, the blockchain provides a way for participants to &quot;profit&quot;, thereby pulling independent participants into the network. Participants are attracted to Bitcoin as they view it as an alternative to another currency (fiat) they perceive to be weakening in value.
Private and Consortium blockchains make no sense to me, but let's say some agency decided they wanted to seed a new public blockchain to do something like: verify that a particular coffee brand came from FairTrade sources.
How would they incentivise independent actors to verify transactions in this chain? Is it the case that they have to create a token reward, and hope over time that the token develops some minimal transactional value, and hope that early adopters make a return? Why would such actors not just participate in standard cryptocurrency blockchains?
It seems like a very hard sell, given the effort involved in running Internet connected hardware.
From where I'm sitting, its hard to see how a public blockchain can have any application beyond replacing fiat currency.
Is my understanding of this correct?
There are a number of research papers that cover the question &quot;Do you need a blockchain?&quot;, e.g. the eponymous paper by Wüst &amp; Gervais (2017) and the extensive Blockchain Technology Overview by NIST (2018). At a quick glance, the article When do you need blockchain? Decision models. by Meunier appears to provide a survey collecting a broad range of answers to the question.
The general gist seems to be that you only need a blockchain if all of the following conditions apply to your use case:

an actual business problem that needs solving
shared consistent state
multiple authors
append-only data
no sensitive information
participants do not agree on single trusted third party

Since blockchains are complex and wasteful, they usually are not a better solution to problems that can be solved building on trusted third parties, audits, and distributed databases. If one or multiple of the listed criteria are not met, your problem can likely be more easily solved using these well-explored approaches. Blockchains tend to be the best approach only when they are the only option.
Meunier concludes a bit tongue-in-cheek that the only convincing application so far is the creation of unregulated money.