And why would one want to do that if not for having persistant objects?

A relational database is just one way to store objects (and a very poor one at that). There is and have been better alternatives out there for many years, so the idea that you should ever have to go through that is just silly. If you choose to, or if your requirements dictate that you do, that is different, but you certainly don't have to use a RDBMS, it is just the most commonly chosen knee-jerk design decision out there.

Languages like Smalltalk and LISP have had OODBs for a long time now and they are used very successfully in lots of real world mission critical apps. And even Java and .NET have a pretty decent and successful OODB out there as well. And Cocoa nib files are really just archived object graphs that the Cocoa framework unarchives when needed.

Perl now has KiokuDB, a production-ready alternative to ORMs that does not suffer from impedance mismatch or any of the other annoying compromises that ORMs force you to make.

My point is really that using a relational database as a dumb object store is neither good OOP or good database-ing. The right tool for the right job, which IMO is exactly what the OP did here.