Most people do not vote - a front page link on HN or Reddit will see 10 - 100x more impressions than votes (my own experience has been 100x+ on the low side). The more complex the material, and the slower it is to parse, the response rate drops dramatically further still because it will likely either be backed out of (ain't got time for that), or more likely when the user is done with it they have lost all context. Those magical tabs you find sitting in the background hours later.
So you're left with the highest response rate being towards short, sweet material that ideally panders to a bias, allowing the user to shortcut even more. This is true even on HN where trends come and go, people trying to evangelize some bias based on nothing more than a title or a skim summary.
All of this doesn't even count astroturfing and sock puppets - the lowest common denominator ascension of content already makes enough noise.
So you're left with the highest response rate being towards short, sweet material that ideally panders to a bias, allowing the user to shortcut even more. This is true even on HN where trends come and go, people trying to evangelize some bias based on nothing more than a title or a skim summary.
All of this doesn't even count astroturfing and sock puppets - the lowest common denominator ascension of content already makes enough noise.