Because to manipulate the topic of the day, it's far easier to make a single article or interview which will then be reposted, rewritten and mixed with opinions countless times without really checking it or even critically thinking about it, than to organize a collusion with evil masterminds on top, involving huge amounts of people.

All the viral trends can be traced back to one-two sources which got picked by influential media, everybody else is talking about it because others do the same. The media always worked that way, it's nothing new, it's just more apparent in the age of hyperconnectivity.