And? before the internet those ideas didn't spread anyways or they were spread by a small number of media companies. Pre-internet was not this mythical golden age of an exchange of ideas. On the whole of it these small number of tech companies are actually pretty hands off when compared to how legacy media operates. In fact now fringe/"banned" ideas spread faster.

Winner winner, chicken dinner. It's obvious that at a certain scale you shouldn't have as much license to censor, as you effectively become the public square. If you run Cathy's Cat forum where you have a thousand users and you want to decree pro cat speech all the time...be as dictatorial as you want.