Exactly this. Blockchains applications which are not currencies are worthless because any extraneous data added to the blockchain can be fake. Only currencies do not require anything to be added.
Not necessarily worthless. You can add a fake piece of information, but it's timestamped. What matters more, it forces you to fake later info related to the first fake piece. You can't go back and fix the logs after the fact. This can be valuable even if the info itself could be fake.
As someone who pays other people to sanitize databases, I disagree. A large database where you know 1% of the data is invalid but you don’t know which 1%, means you have to validate the entire database from top to bottom for mission critical applications.
So any errors in a database can easily invalidate the entire database. It all depends on the severity of the consequences of relying on bad data. For non-mission critical stuff, 90% correct might be just fine.
For a blockchain application where people are putting their trust and faith in the blockchain, that sounds mission critical to me.
Of course, a certain fraction of bogus data makes a database worthless if you can't locate it and fix or erase it.
I'm trying to make a different point: legitimate uses of blockchains - unlike THE blockchain: maybe not permissionless, not PoW based etc - for specific application. An example: tracking deliveries.
Admitting you can fake one data point - parcel was here at this time, weight was such-and-such or whatever - you either have to extend the lie OR the world notices something's fishy at the next milestone. All that is required in this case is a posteriori immutability, not absolute accuracy.
i have difficulties following your thought. there is no legitimate use of blockchains because they are clunky, slow, inefficient databases. databases have been invented and used and evolved.
-if a blockchain is not permissionless, why use it? you need a central authority to control access to a private blockchain. if you got a central authority, you might as well use a regular shared database
-if it is not POW, it is not secure. if it is not secure, why use it?
there are many scandals in the production and delivery/logistics of food. lets say we want to make sure that EGGs are really produced in a ecological fair, animal rights fair, "bio/eco" means of production. that is expensive (you need more space, have less production, more costs - the bio-eggs end up being twice as expensive. no problem, since the environmentally aware customers are happy to may more for their fair produced eggs.
problem is the declaration of the eggs. every scammer can forfeit the declaration and sell the worst mass farming, cruel production eggs as the very top notch "bio"/eco" egg. how could you prevent that from happening?
using a blockchain? yeah, you could print a private key on each egg or a public key or whatever you choose. how on earth would this keep a rogue egg producer from scamming? he could just print whatever code on his cheap eggs.
if it is not a rogue producer it could be a rogue food logistic company. they could flip the good eggs for bad eggs while transporting them. who would know? the blockchain would not notice it. it cannot enforce honesty on the eggs. if you use the bitcoin blockchain, it can only enforce honesty on its token, the bitcoin.
a rogue player would not need to alter the data. he can alter the stuff that gets delivered. the database consists of data entries or tokens. it cannot enforce anything outside.
