... together with a trusted third party covers something like 90-95% of the supposed applications if blockchain. It's insufficient for typical mass-adopted, international currency, but for damned near everything else it is "more than good enough".
In the real world, before blockchain, what mutually distrusting corporations or people would do is set up a distinct third party organisation to keep the "ledger" (or whatever).
For example, banks use non-bank companies like Experian to do cross-bank fraud analysis. Similarly, many industries send their sales stats to a third-party non-competitor org that aggregates the data, and then sells back industry-wide anonymised sales stat reports. This lets companies that don't trust each other exchange data, etc...
This was a solved problem centuries ago, and technologies like Azure SQL Database Ledger make it nearly as robust as blockchain, with none of the downsides.
In other words, the NIST flow chart needs more steps towards the bottom pointing to both existing and new non-blockchain solutions.
In the last few steps, going from “Yes, you need trust-less updates” to “<tiny distraction>” to “Meh whatever, just use a regular database!” seems a bit lacking in short-term memory…
Well, if you need more proof that you don't always need a blockchain, Webcash ( https://webcash.org ) might be it because Webcash just uses a central database for double spending detection. A few of the early users were commenting that the project has put lots of altcoins to shame from an architectural standpoint.
Storing the list is the easy part. I have a usb drive that can store the list.
You want people to agree on which chain is the main chain, so that you can only add things to the list, and you can't go back or substitute it with another list without breaking proof of work.
The purpose of bitcoin is to make people agree that a spent transaction is irrevocably spent.
Crypto is more and more centralised because the hardware to run your own node is now thousands of dollars. That is without even getting into miners...It is kinda failing.
This chart is kind of dated and misleading at the moment.
1) You don't need an archive node to fully verify the current state of the chain. A full geth node in full sync mode (about 600gb) will process every transaction of every block and get you the current state. You only need an archive node if you want the history of each account and contract separately indexed.
2) Folks that do want an archive node can now use much more space efficient clients then geth such as erigon (1.4tb) or besu (1.2 tb) if they want to run a block explorer or query the state of an account in the past.
1) you need an archive node to get historical events which is the only way to do lots of things. E.g. scrape all NFTs
2) Erigon has horrible bugs and is missing data. I filled a ticket against one such issue and they "fixed" it by making the exception go away and returning null. Their lack of attention to detail made me abandon the project.
If you know someone in the project I can produce MANY examples and would be willing to do so because running an archive geth node sucks.
I don't know any of them directly. But they do have an email on their github readme that you can send a request to for an invite to their discord. And if they don't respond on that, you can reach many of them in the Eth R&D discord.
For the purpose of validation. If the transactions didn't need to be stored in full for validation they wouldn't be stored. You can see with newer upgrades to the Bitcoin blockchain like taproot you can have validation without storage
NIST's answer to "Do you need a blockchain?": https://m.imgur.com/a/RlUj9Ed