I prefer a separate DB instance for each app. Each app is on a separate ZFS filesystem so I can snapshot/backup the app data and DB together as one.

A possible restore only affects that app. Plus I can guarantee the files and DB were snapshotted at the same moment this way.

It may just be a way for me to avoid managing the DB.

I do the same, a single app on a zfs filesystem I can snapshot/send/receive