Nothing stops you from having a verifiable audit trail in a SQL database. You could even decentralize the audit trail.
Problem with Ripple is creation of new XRPs, they had full control over that.
How do you decentralize the audit trail? Would need something like ripple
Generate a cumulative checksum of everything that happened yesterday plus the previous day's checksum, and post it in the local paper, on your website, and in all investor documentation.
Eh, last I checked the five primary validator nodes are all run by Ripple.com. Not really "POA" when there's only one authority IMO.
So, a database plus digital signatures.
so a sql database
So files with indexes... so storage devices with a file systems... so... so bits of information...