Actually, I have the answer to this, I have just found it at the time of posting this thread, as a matter of fact. I want to point out that a ColorRamp node will actually do the trick, but this will be different from how I ran into the eye gradient texture, seeing as legitimate image textures are not present here.
As promised, I intend to answer, once and for all, how to attain a gradient texture for world backgrounds. I had found myself searching through a few Blender Stack Exchange threads, and this one in particular did the trick:
If you check that link to a different Blender Stack Exchange thread, you will notice the same setup being used for an object. I had previously overlooked that, believing it to be impossible for use with World Nodes.
...I was wrong.
Not only could you use that node setup to achieve a gradient background, you can also use a Mapping node, personally best set to point, in order to rotate, scale and position it as you please. Here, see for yourself:
Using Normal allows you to properly use Rotation to legitimately rotate the gradient, though it does not seem to stay linear. Using a Gradient Texture node does not work with any of these nodes, as far as I have currently determined.