Why isn't putting that data (or a hash of it) in a publicly available git repository just as good? You can even publish the newest branch hash in the newspaper everyday if you want.
And for data loggers not connected to the internet this helps. It would be just as good to put it in a central repo if there was an internet connection available. But if you're logging a refrigerator temp on a container traveling between countries there isn't going to be a cheap option for internet.
Every git commit contains a hash of all the previous commits, and is itself referred to by a hash. So if you change an old commit, all commits descending from that get a new hash, and so a new identity.
If you publish the latest hash in the newspaper, you've locked down all the previous commits also.
You are correct.
We understand that... GP even said:
>> I get the value of having a chain of "blocks" of data
How does a consensus algorithm help when the nodes are not connected to the p2p network?
Speaking of trusted parties, (multiple) of those could be set up using a chain of trust in every network segment that do as much cross-signing/-verification as deemed necessary. Once it goes online again, the performed operations could go on-chain.
You can't just create a proof-of-work blockchain to hold your records. That blockchain also have to be a functioning economy with a large enough market cap to pay out mining rewards that are large enough to make a 51% attack economically nonviable. If you fail to do so, or the economy falls apart, all tamper-resistance just disappears.
It actually ends up being cheaper just to trust a group of authorities, and pay auditors to make sure they are being trustworthy.
There are lots of industries where tamper proof records are valuable and record keeping is distributed.