When your job is to get people to pay attention to you, why would categorize anything as less than the most important? Crowd-sourcing the importance might be better, but that brings us right back to a HN/reddit solution.
In practice, attention is credibility. You can look at this as a cultural problem[1], a psychological finding[2], a propaganda tool[3], a business model[4], etc.
I guess credibility is a poor word choice. I meant something more like trustworthiness (which might tend to build credibility with a certain demographic...).