Coming Soon: A Faster Web (not a moment too soon!)

Question Everything:
If there's a conflict loading a page containing images and other elements, and the one is being loaded before the others, slowing the process, why couldn't we have the whole page, images and all, formatted ready for display not as separate elements requiring different treatments during loading, but as one thumbnail PNG which, once loaded, would be automatically resized to fit whichever size of available screen your device uses? Could we do that?