I don't know if Google news still has the feature, but when I used it, there was an option to raise and lower weights to certain news outlets. I found it worked less and less over time to the point where the outlets I specifically filtered on didn't even show up.
I don't believe this is simply an effect of giving the crowds what they want.
The controls have gotten less granular, and I don't see a way to add new sites to the filters without an article showing up in your results first. But they do still seem to work on personalized news such as the "For You" section.
What I have noticed is that the filters don't seem to apply if you click on "Full Coverage" of a topic anymore (via the little icon with the colorful rectangles), perhaps in response to those echo chamber complaints.
I don't believe this is simply an effect of giving the crowds what they want.