The decentralisation process and these affects has been going on forever.

First we had the really old days, where few books were printed at all and at great cost. Less misleading information in print, but not very democratic.

Then the printing press and more people could express themselves. So misleading books and documents became more common.

Later the media grew, and with it the amount of sources went up even further. Niche publications that spread 'unpopular' opinions appeared and misleading info spread further.

And with every medium since, the effects grew. Radio, TV, the internet in general, social media sites. Really, it's just an inevitable consequence of less gatekeepers and more people being able to publish their thoughts.