The peer review process is put in place to evaluate the legitimacy of statements made and results found in a study. It is important to be able to distinguish what the purpose of the paper is and what the authors’ thesis statement is going into it (if there is one).
Anything stated by fact needs to be backed up by a legitimate reference to keep false information from being accepted as anything else but false. The entirety of the references list, in fact, should be combed through to ensure the efficacy of the claims they supposedly support within the paper.
Any informal language used should be corrected and any overly scientific language that the author cannot expect the audience to know should be explained.
The benefit of having a peer review system in place is that it can confirm the validity/credibility of the results rendered so that anyone referencing this paper down the line, or just reading it to gain knowledge in general, is not incorrectly informed. It stops false information from essentially snowballing.