In older drives, a lot of failures were down to the heads actually getting stuck on the platters.
By freezing the drive, the metal would shrink just enough to unstick the head. Of course the location where the head crash had happened would be corrupt, but the rest of the data would be fine (mostly).
I literally squeezed the data out of a drive once. 40M Connor, one of the first IDE drives. If I squeezed it too much, “Data Error, Abort, Retry, Ignore”. Too little? Same result. Just right? In like Flynn!
I spent 40 minutes copying that drive, got every bit back.