I think OPs argument is that the content is low quality, which is damning, but not in the same way as it would be if the top content was political or "disinformation." Benign garbage is still garbage, but we should not really expect anything else.
why is “benign garbage” (in your completely subjective opinion) “damning”? That implies a certain level of intentional wrongdoing on behalf of FB. What did you expect the typical online social content to look like?
Yes, it is my subjective opinion that "typical online social content" is benign garbage and I think this report from Facebook is "damning" evidence supporting that opinion. I'm not naive enough to believe that giant social networks will produce anything else, but I don't think that's an excuse that keeps us from being critical of the networks or the content on them.