Are you curating the list of publishers somehow? I would imagine the AP/AFP newswire repost circuit/echo chamber would result in overestimating importance of a lot of crapola and underestimate the importance of investigative pieces for example.
This was an issue when I first started. With minimal sources a lot of time the top collections were low quality SEO articles.
After adding a sufficient amount of sources I've noticed a decent reduction in the echo chamber. Although by ranking importance by the most talked about topic, it is going to have some sort of echo chamber.
Adding left and right leaning publishers for instance has helped. Although one might say something is good and something is bad, the embeddings pick it up as the same topic.
