And a literature review is part of what was done, always. If what you said were true, there would be no point in a literature review at all. Instead, every paper includes one because researchers understand it's an intrinsic part of research. That's what makes it research instead of just search: research is a systematic process that involves, in every definition of the process I've ever come across, a literature review. I challenge you to find an example of peer reviewed research that doesn't contain one.