Now because it's only been a short time since people could decide anything. Or at least were told that they could. How long since real parliamentary democracy, where say half of people who can currently vote were allowed to do so?
And in that time, the major outlets were few and gated by a journalistic system where you had to at least say something sensible and be judged by what some might call an elite, but others would call educated common sense.
Recently that status quo has fallen apart, and it's become clear that you don't need to have a message that is in any way cognizant of history, science, or any other established facts. The crazies at Speaker's Corner are now able to broadcast with a similar reach as people who've actually considered what to say.
Technology does indeed have a lot to do with this state of affairs, and is also alluded to in the article. That one nutter who says the world is flat online now causes others with the same inclinations to gain in confidence. Likewise with any number of ideas that would have quietly died.