The point you make does not lead to the conclusion that this is not newsworthy. We still understand very little about why certain things work, that have been proven to be clinically effective for years. For instance, the creator of the extremely effective treatment EMDR (Eye Movement De-sensitization and Reprocessing) did not initially know why the treatment she discovered had the effect that it did. She had theories as to why it worked, but could not say for certain. Through years of clinical testing and fine-tuning, however, she was able to prove unequivocally that it worked with extremely high success rates, especially in the healing of treatment-resistant PTSD. After many years, advances in neuroscience have given more answers as to why the treatment works the way it does. I imagine this is what the study is showing in this instance as well. We have understood for a long time that medicines can achieve repression of the intrusive thoughts in many anxiety and mood disorders. Many also had educated theories as to how those results were achieved, but the discovery in this article is some of the evidence to prove the theories right or wrong.