When you're researching a topic for the first time, you might conduct a Google search of a few keywords. This search usually pulls up a Wikipedia article that gives you an overview of the topic and its historical context.
You search for background information in scholarly databases for the exact same reason! Why stop at a Wikipedia article when you can compare many different sources?
Background information helps you become more knowledgeable about a topic before you start putting together a research project. Your search for background information can help give you ideas for a thesis, or bring up supporting evidence you hadn't considered yet.
Looking at different reputable sources and comparing the information they give you also helps you establish the commonly agreed upon facts. For example, look at two background sources below, written about the same topic.