In article , PeterN
wrote:

My guess as to "why?" is that the competition committee wanted to
provide some parameters so people wouldn't ask "What ppi should I
use?".

that's a stupid reason.

such a question is an opportunity to teach the person asking what ppi
really means and why it makes no difference in an image that won't be
printed.

True, but some of these images will be printed.

it still doesn't matter, and at 1024x768, they won't be printed very
large (or they'll look like crap).