Technically, any use of a drive shortens the MTBF (Mean Time Before Failure, I think). But, as someone said, nowadays that's a huge number. Drives aren't guaranteed beyond that. But they will all eventually fail with use from simple wear and tear; they have moving parts and spin platters at incredible speeds and high temperature.
Low level formats aren't possible on new drives; bad sectors are mapped out by the firmware. Each cylinder of a disk has extra sector(s), and when a sector begins to fail, it is moved to the fresh sector and re-mapped. When the extra space on one cyl fills up (drive is really going bad) it borrows the next cyl's space. I'm not sure what that means to the defragment programs, but I assume they handle it properly or are completely blind to it.
I agree that formatting is no more damaging than any other function. Less than my StarCraft II game, by far!