In the real world, DB's servers are more likely to be breached than file-level encryption, by orders of magnitude. So encryption would be a very welcome additio

In the real world, DB's servers are more likely to be breached than file-level encryption, by orders of magnitude. So encryption would be a very welcome addition. Unfortunately it has a very real cost for DB: data redundancy could no longer be leveraged to save storage (because 2 identical files would appear different to DB). I suspect at their level of scale that would move a few cells in their CFO's spreadsheet.