You never need to low level any HD.
In the old days you bought an ST506 hard drive, which acted like a big floppy disk drive and then you had to buy a controller to go along with it. Like floppy disks they then needed to be formatted and the controller defines the format of the data. Each manufacturer could do things differently, so if you swapped controllers you needed to format it again.
It's done at the factory now, low level formatting hasn't been required for 20 years. i.e. since the drive controller was shrunk and stuck to the bottom of the drive.
You usually don't swap controllers between drives these days, apart from data recovery. In which case you have to swap it with an identical one. Partly because the formatting is different, but also because now there is no need for a standardised connection to the hard drive and lastly because the controller firmware is stored on a hidden part of the drive.
If you could low level format the entire drive, then you'd wipe out the controller firmware. At the factory they can bootstrap a drive from scratch, but they keep that secret.
Hard drives also do transparent remapping of bad sectors now & the bad block map is also stored on a hidden part of the drive. In the old days the drive would come with a sticker that listed the bad areas and after a low level format you would be prompted to type it in. Now they don't advertise how many bad blocks there are and low level formatting would lose the hidden copy on the disk.
The SCSI command for low level formatting these days probably just writes a pattern to the good data sectors on the drive and doesn't actually do a low level format.
