I'm so sorry if it's the wrong flair!!

Today I made a task that used TestDisk to retrieve an external ssd that was cleaned using Windows DiskPart. The client saw a tutorial on YT and tried to made the same thing, but the poor boy formated the wrong disk.

I used TestDisk and that was a simple task to do, and so easy, but make a great question on my head.

On DiskPart we have clean and clean all

Clean delete boot code, signature 0x55AA and protective PMBR(GPT AND MBR)
Clean all delete the same thing that clean delete and the data on the storage.

The question is: why hackers couldn't use clean all to delete the data storage?
If the SO can't locate partitions, why they can be retrieved?

I'm sorry if this question is a fool, but it's a real question from a IT guy