I think the argument would be that formerly corrupt enforcement entities, or entities with no track record, would use a blockchain as proof of their commitment to impartial enforcement going forward. "We know you don't trust us, but here is a public record that you know we didn't manipulate, so if we are going to steal your land we have to do it openly."
That said, the same thing can be accomplished by outsourcing the public ledger to a third party with a reputation for trustworthiness. The same way that countries that cannot make a credible commitment to not devalue their money will often peg their currency to the dollar or the euro.
A blockchain might go part of the way to solving that problem, but as you say there are other solutions (any public database can be monitored for record changes if that trumps privacy concerns, and non-blockchain databases can be append only) and transfers of property ownership aren't necessarily consensual and compensated just because immutable public records are made of them. And if it's landowners rather than an untrustworthy oracle updating the database with records of land transactions you create a new class of problem (if you lose a private key is that land yours in perpetuity? Or is it someone else's in perpetuity if they steal your private key or exploit a bug in a related smart contract and won't give it back?)
Which is where trusted counterparties like the one you suggested are a much better bet than an untrustworthy party enforcing and administering a record and its exception handling, even if that record itself is immutable.
