I can't believe shit like this gets modded up. People like you - the ones who blame the user - give people like me a bad name.
They put it on iCloud - as far as they know, THAT IS A FUCKING BACKUP. They have independently set up an iCloud backup, as far as they are aware. Calling them stupid does nothing to address the cause, which in your example, is a shitty user interface provided by Apple that did not adequately inform the user of the effects of the action in question.
No, they do not "deserve" this. They made a simple mistake. We all do. Believing an iCloud copy is a reliable backup is a perfectly reasonable assumption to a layperson. They have a copy on their iPhone, and a backup copy in an iCloud account. Or conversely, they have a copy in an iCloud account, and a backup stored on their iPhone - THEIR OWN FUCKING MEDIA.
You seem to not understand that not everyone should be expected to maintain the level of knowledge you have on this matter. They don't understand it - so they place their trust in Apple - who, by all accounts, should know a hell of a lot more about this matter than they do.