For instance, say you are writing a paper on how point of view affects a short story. One would assume you go to JSTOR or googlescholar and search "Point of view." However, that brings a whole stream of useless articles on topics outside of literary criticism. So you add more keywords, perhaps something more specific to the point of view like "Child" or "woman" or "father"; whatever "point" you are "viewing" from. Now you have no results at all.
Would one instead look for an article or book that deals with the topic more abstractly? It seems like a faux pas to not use sources, especially on longer essays.