IMO public discourse is less controlled by private corporations/organizations now than at basically any other point in our history, with the possible exception of like, 10 years ago.
There was never previously any realistic method for a private citizen to gain a platform to meaningfully influence discourse. Traditional media _literally_ defined the narratives in play. I’d argue that a whole lot of the ideological carnage and polarization going on is directly a result of the “democratization” of public discourse.
While there was some oversight, the reality is that news media still had basically total control over whatever narrative they were interested in pushing.
In fact, I’d argue that a lot of the ideological chaos and subsequent censorship we have seen recently is precisely a result of private corporations losing control of public discourse.
The truth is that before the internet, there wasn't really any genuine public discourse. If you wanted any reach at all, you had to go through a gatekeeper of some sort.
Newspapers/tv/radio were, and no one was giving nazi's equal time on every issue.
Newspapers only ever published what they wanted to, censoring any viewpoint they felt like censoring.