I didn't say that it was finished.
Hard drive problems...or what appears to be hard drive problems...can also be a problem with the file system (NTFS). Trouble with either will result in unpleasant feelings for the user.
The purpose of the diagnostic...is to confirm/refute any suspicions one might have about the drive itself.
Any key hardware item (PSU, CPU, RAM, motherboard) are always suspects when things go wrong. I just like to start with the hard drive as my initial suspect because that's where all the files are
and drives can develop problems more routinely (IMO) than the other components.