evolution

Standard economics. As you start penetrating potential audience its going to get saturated after some point until you reach all of the audience. As impressions to get one more click are needed more, google needs to exhaust their inventory more. Apparently CTR is going to degrade, and google will start increasing marginal cost per click. Cost per click is curve is often going to be marginal cost curve, where maximum profitability is at lowest point on the curve. Its not about profitability of google adwords but the profitability of the media you're bidding for. When saturated you can always expand your potential market (audience) by adding more keywords/placements.

I tried logging in -- persona sent me email of confirmation, when clicked it redirected to ebookglue which alerted 'login attempt failed'. you might want to look into that.

yes, there are lots of publications that write quality articles but don't have place to weight them based on community opinions. every article has comments, but those wouldn't be in order of priority of reading. also business news are big enough so that every publication eventually covers it, what remains is the community insights about the news. that is why I like hn -- because of community opinions than content that is posted.

Or can it be that they never gathered as community, like hn?

yes, thank you for the idea. Although I'm not quite sure undergraduate students here contribute much to the open source projects.