No one in science counts up the number of studies and says there are so many in favor, so many against, thus the greater number wins! Shall we do it by number of pages? Of course not equally absurd.
There are false equilalencies being promoted here. The other fallacy is that one paper cannot change things. It certainly can!
Again, we hear this as the world against WPI, again you fail to mention that two other labs, the Cleveland Clinic, and the National Cancer Institute, their researchers, plus Science magazines peer reviewers all were engaged in the work required to publish this result.
The other studies methods and cohorts were well critiqued by parvofighter (so much so that foreign press picked it up!) and others here.
XMRV has been found, is being found in patients with ME/CFS. This should not be in dispute. What to make of that is where the science is now proceeding.