There were timestamping services which people paid for before bitcoin.
So, there is some price people will pay in order to be able to demonstrate in the future that some data existed at or before a given time.
A decentralized ledger also provides this purpose.
Of course, at current transaction fees on most blockchains, it would be wasting quite a bit of money to make a transaction just to timestamp a single thing.
This is why there are services (one of which, iirc, has gotten a, uh, endowment(?) in order to provide the service for free?) which collect large quantities of (hashes of) data that people want to establish existed before a given time, and produce a Merkle tree of all of that, so that all those people can demonstrate that their data existed before a given time.
So, that's one useful service.
Is it enough to justify all the stuff that goes into blockchain stuff? That's a different question.
But, if the question is "Do they have any genuine use?", the answer is "yes." .
The blockchain is a pretty terrible timestamping service as the block time varies based on the current hash rate and difficulty. From as little as 5.5 minutes to as much as 15 minutes. [1] It's at best a coal-powered monotonic counter. Given the massive variability you have to correlate it with an actual clock you trust lol, and if you trust the clock you may as well just use that.
by timestamping I didn't mean in terms of, getting the most precise time possible, but in terms of a very difficult to fake-in-large-ways timestamp.
I have at least slightly more trust in the bitcoin blockchain not having the times be falsified in a major way than I do for any of the centralized timestamping services where you are trusting the security of those companies' timestamping servers.
The reason why I say "slightly more" is because I do have a pretty large amount of trust in those timestamping sources.
Bringing up the coal-powered is irrelevant to my point, which is not about whether it is worth it, but whether it has any uses.
So, there is some price people will pay in order to be able to demonstrate in the future that some data existed at or before a given time.
A decentralized ledger also provides this purpose.
Of course, at current transaction fees on most blockchains, it would be wasting quite a bit of money to make a transaction just to timestamp a single thing.
This is why there are services (one of which, iirc, has gotten a, uh, endowment(?) in order to provide the service for free?) which collect large quantities of (hashes of) data that people want to establish existed before a given time, and produce a Merkle tree of all of that, so that all those people can demonstrate that their data existed before a given time.
So, that's one useful service.
Is it enough to justify all the stuff that goes into blockchain stuff? That's a different question.
But, if the question is "Do they have any genuine use?", the answer is "yes." .