Jewish power got spooked by people discussing things freely without the Jew filter their monopoly on old media had previously provided. So they used their massive wealth to buy it up, use it to spew 24/7 propaganda, and then censored anything they didn't like.

That's kind of an over simplification of it, but that's the gist of what happened. This hysterical Jewish reaction accelerated dramatically with the rise of the alt right and populism fueled by the internet.