Seriously? Do you even pay attention to the sizes posted in every thread?
Original-sized art rarely fits basic monitor resolutions, plus there's dozens of resolutions out now between all the phones & tablets. Then account for cropping to eliminate visual garbage ...
It's amazing that even half the posted wallpapers conform to standardized sizes. Given how easy it is to edit images these days, it's completely irrelevant, too. Only a complete retard is incapable of taking a decent quality original and customizing it for their needs.