A 'debate' which exists within photographic circles is about performing a 'format' which is to overwriting the file allocation table (FAT) with a new one plus some (but not all) storage areas within it vs. 'deleting files' which marks a space as available within the FAT. Contrary to what you may have been told, it has nothing to do with zero'ing out a card or completely overwriting data on a given disk/card. Special tools are required to wipe a disk back to '0'.
Unfortunately, those involved in this 'debate' are experts in the field of photography rather than electronics or computing. Particularly this seems to be true for those who seem to carry the most sway...
The proponents of formatting suggest to do it to prevent file allocation corruption issues, but if you have FAT corruption problems then you've got far bigger problems waiting for you that could bite you after each and any click of the shutter.
The opponents of formatting say that excessive writes to a card are a bad idea, which while noble, betwen wear levelling and other techniques and the low volume use of even a professional's cards wearing a camera out is more likely than a flash card.
The reality is do what you like - it makes no difference in the real world.
Incidentally I have experienced FAT corruption issues with my DSLR - for some reason this camera in combination with a (supported) 16gb card will, at some seemingly random point, throw up an error and refuse to shoot any more. Formatting the card cannot prevent this behaviour becasue the camera is the source of the problem. Incidentally the files are fine and popping the card into a reader lets me get everything off it and obviously at that point I delete all the files off the card and the problem is gone and I may then be able to go on and shoot a whole card-full (or not, at my camera's discretion).