Earlier quoted context omitted.
It doesn't have to be the case of no backups. Many different things can happen... They could have a faulty backup design. They could have lost the backups. They could have a fault in their backup verification / checking procedure. They could miss some part of the data that wasn't crucial before, but after a couple of updates, they cannot restore contacts without it. Etc. There are many ways this could have happened -…
As far as I'm concerned, if you can't recover your data, you don't really have a backup. That covers every one of your hypotheticals.
In practice, you don't know if you can recover your data unless you migrate the whole company to the backup copy and ask them to check every functionality they use -- every time you make a copy (and rely on them doing 100% coverage). The best you can have during the normal operation is a high probability that what you get is a proper backup, because that would be the case the last time you did a full test (if you ever did). Datasets change, ways of interfacing with data change, etc. Testing is not perfect either, because your tests can be broken or can be reporting false positives.
So yeah... noone can be sure they can recover the data. Does that mean that noone really has a backup?