Propaganda from deep-pocketed individuals and organizations is a problem, but the current cure is worse than the disease, particularly when the censorship itself is biased. It takes more to be labelled fringe and justify censorship for left-leaning speech, than it takes for right-leaning speech.
The root problem with modern discourse and social media is subtle, unforced siloing of communication within subgroups, so that there's not enough subgroup-bridging discussion. Overton windows shrink until subgroup-bridging discussion is mostly impossible. That all happens without any active censorship.