[madarco]

I think the best use case is when collaborating on the design with other devs, it's very easy to understand and to manipulate together during a meeting.

But also I found them useful as an onboarding tool: a single picture to describe the db, for eg. autogenerating them from the db FKs.

Granted, you can just look at the schema of each table, but having a single picture to look at will save some time and help memorizing the relationships.