A newspaper asks itself “why should I publish this??”
It costs to publish, time, management resources, labor, time on presses, ink, paper, and so on, so it is a key decision, with implications if you get it wrong. An individual by contrast can now ask themselves ‘Why not publish this?” There is no cost, just a bit of time, and the return is you can be a “published” journalist or Photographer or movie-maker, the downside is zero.
The removal, by the availability of the web, of the organizational and transaction costs required to assemble the physical materials to publish a newspaper has driven this reversal. It costs nothing to write a blog, put a photo on Flicker, so why not just do it?.
This simple reversal, “why, to why not” has changed the world.