The problem that arises when you define censorship broadly is that the opposite of censorship is censorship.
If no one can restrict what gets published in their venues then as soon as a venue starts discussing stuff I don't like, I can spin up a shill call center or a guy with a thousand accounts and a copy of GPT2 and flood that venue with so much divisive moronicism that the voices that threaten me will be almost completely drowned out.
Worse, large open venues being flooded with low quality communications already happens even without any intentional censorship-by-flooding attack. ... providing great cover for these attacks. Especially savvy attackers can leverage the pre-existing populations of well meaning fools by shaping their messages to motivate fools into carrying on the disruption on their own.
If you think about it-- the classical view of censorship where someone outright silences you is nearly impossible online today in most of the world. It is extraordinarily hard to completely stop the spread of information that people want to spread. But at the same time, censorship that works by flooding out an idea or discrediting it by association with abusive nutballs has never been easier or more effective.
When we worry too much about private parties shutting down conversations in their own venues we risk improving the situation around an outmoded and somewhat ineffectual model of censorship at the expense of making a modern and highly effective model much worse.
The best I think we can do is foster an internet structure where everyone can have their own venues which they can operate under whatever rules they think are best, and everyone is free to move among them at the lowest cost possible. That way, effective moderation can shut down flooding attacks and voting-with-your-feet can shut down overly censorious (or overly passive!) moderation.
Unfortunately, the highly centralized world created by the popularity and network effects of sites like facebook, twitter, and youtube are the opposite of this. Instead of people being empowered to self-regulate abuse and migration being easy, people are disempowered and migration costs are high.