It's important to note that this is about fake reviews; not necessarily "fake research". There is an important difference. Fake research (eg. people fabricating measurements) often passes real peer review and is a different problem.

The authors committing review fraud probably are not trying to publish fabricated research; it's more likely they were attempting to make it more likely that their research is published.

Most articles are not rejected by reviewers because the research is "wrong"; rather because they are not significant enough, or other papers are better.