I don’t have any respect for the viewpoint that “durable” is equatable with “stored on disk”, and I don’t want to spend time accommodating that viewpoint. It is just an oversimplification in a very bad way.

AFRs and discussions about different failure scenarios are the bare minimum. The bare minimum for scenarios is disk loss, total machine loss, and data center loss. This is just my take on things. I don’t care if something is on disk or not. I do care what happens when a sector on disk goes bad, when a faulty power supply destroys all the disks in a machine, or when a data center floods.

That forces you to think about things like whether you want to turn on synchronous replication.