[mirekrusin]

PoW is never used for private/custom blockchains, I've never seen it, it doesn't make much sense. If you insist on saying it's just like sql, you'd have to say it's "just like" replicated, multi-master sql database, with publicly exposed read only access, forbidden deletes/updates, inserts restricted/enforced by triggers/whatever based on asymmetric cryptography of currently connected user.

It's just not the same thing, completely different security profile.

The only way to forge transaction is to steal private key.

Nobody is saying that blockchain will force humans to not click "organic" checkbox for non-organic mangoes, this is absurd - but it can encode digital signature of somebody who checks it so it can be later traced back and allows to write logic that signature is required for the mango to go to the next step in the supply chain for example.

I think you don't realize (most people don't) how many problems this little thing solves.

It's not replacement for sql, big data or what not - it would be silly to say that - when designing blockchain systems you actually spend a lot of time on finding the most minimal thing that has to be stored on the chain for your contracts to enforce all required logic. It allows you to trust data in it without security ceremony/setup.