Well that's 3d tho. So his only options are to slice one image up, or to piecemeal several objects together, IE tree here, rock there, cloud up there, etc.
That may actually be better in some cases, given you can use things like a gradient, or tiled background for larger portions that don't have a lot of detail.
For instance if you wanted a starfield you would quickly run out of ram if you loaded a huge image, or cut up equivalent, but you could reduce that to a fraction if you just make the background a dark color and placed stars etc. as sprites. And that is essentially what 3d does.