The same scenario you described works just as well if there’s a central SQL db.

It doesn't though. Records can be altered. Names can be changed. Bob owns the fish pond until someone with access to the database erases his name. With a database, the ownership depends on who has access to the database, and how much that organization is trusted. If Frank's party gets swept out in a coup, Charlie can make himself the owner of half the town - after all, he was loyal to the winning side and who's gonna say shit? If Bob wants a loan for fish food, Gary's Happy Imports has only Charlie's word that Bob owns the land he's staking which means Gary's business choices depend on their read of the stability of the Charlie administration.

Let's put a blockchain on it

Frank may be out, but Bob's ownership of his pond is indelible. Charlie can try and say he owns half the town, but Gary can audit the blockchain. So can everyone else. It's no longer worth Charlie's time to shake everyone down because anyone can see he doesn't own shit. Better yet, whatever database Frank used to hold property records dirtnapped the minute the tanks rolled but the blockchain is on 8,000 computers from Arizona to Zanzibar.

Either way, the source of authenticity isn’t inherent to the blockchain itself

Yes. It is.

but to the security of the implementation and the agencies that are providing consensus.

And if 4,001 of them say Bob doesn't own a fish pond, Bob doesn't own a fish pond. But if 3,999 of them say "Bob doesn't own a fish pond" then 3,999 of them get kicked off the blockchain, eat shit, pay their penalties and download the copy of the blockchain that says "Bob owns a fish pond" if they want to continue.

All tech is like that.

Distributed ledgers are not "tech." They are a novel approach to verification that negates falsification. not inhibits, not minimizes, negates.