It should never be assumed that any single source of information is authoratative, moreover it should probably be assumed that information coming from a limited number of people may include the biases of that person or group.
The current peer review process is an attempt to remove as much of the subjectivity from the findings as possible by introducing independent reviewers. Does it work? Somewhat.
Peer review has its own problems; I once turned down a request to review a study because it contained material I simply did not have expertise in. I voiced my concerns to the editor of the journal who assured me that this was not a problem.
I know of one example of a reviewer trying to inject their own research into a study where it was tenuously relevent. The amount of work required to add this material was not trivial.
Ultimately, people are still involved in science. However, science is self-correcting: Can't reproduce a result? Results and conclusions are then considered poorly founded. Researcher found to have ulterior motives? Their entire past work and any future work will be subjected to greater scrutiny. Don't ever underestimate how invested people get in their own pet theories either.
The scientific process is not perfect but it's the best solution we currently have to removing the people problem.