I expect all usages of this tool to border on fiction in some way. After all, the images don't depict anything real. They might accompany a nonfiction article as an "artist's impression," though, as so often happens in popular science articles about things we have no images of yet.

It's become increasingly common to start off articles with an image, even when the article is describing an abstract concept, just to avoid having a "wall of text." If that's what you need to do, it seems like a more interesting alternative to clip art.