Why would the data disappear, given that it's stored on an external volume (i.e. EBS or Google Cloud Storage or just a directory on your laptop), not in the container FS?
I simplified, because in the end that would be the equivalent.
The danger is that some bugs in a filesystem, manifests themselves only when there is abrupt termination, otherwise things appear normal. Stuff like data is being written in incorrect order, or data is synced to disk at wrong time, or not at all.
On top of that user also expects performance, so some shortcuts can be taken that compromises the above (especially if the criteria is that docker is intended for stateless applications).
When there bugs like that and things are abruptly terminated, the data on the disk can be heavily mangled to a point that can't be recovered so essentially it would be lost.
The danger is that some bugs in a filesystem, manifests themselves only when there is abrupt termination, otherwise things appear normal. Stuff like data is being written in incorrect order, or data is synced to disk at wrong time, or not at all.
On top of that user also expects performance, so some shortcuts can be taken that compromises the above (especially if the criteria is that docker is intended for stateless applications).
When there bugs like that and things are abruptly terminated, the data on the disk can be heavily mangled to a point that can't be recovered so essentially it would be lost.