They do gain some data security as they've effectively sharded their database by user. So at the point of a power failure only the active users' data would be

They do gain some data security as they've effectively sharded their database by user. So at the point of a power failure only the active users' data would be at risk of corruption at the file level. Of course there's always the risk of damage to the media in general, but then you can never fully protect against hardware failures.