You can't use the common carrier argument to force someone to be a common carrier. If you pick and choose your clients based on policy you are by definition not a common carrier. Mailchimp is a private carrier. They choose what to carry.
Agreed -- but a lot of social media sites say "we just connect people" and then turn around and are forced to play moderator so things don't burn out of control...
I don't know why social media companies haven't tried letting users opt out of different categories of censorship.
Presumably every user appreciates the anti-spam filtering these sites do, and anti-scam/phishing, but there should be a separate checkbox (ticked by default) for "Remove misinformation about covid/vaccines", and one for "Remove misinformation claiming the election was stolen", etc.
Then the social media companies can say to governments "If you would like all users in your jurisdiction to be unable to opt out from these categories, please pass a law requiring us to hardcode these settings for them, and we'll update our UIs to tell users why they can't opt out."
Better yet, the social media companies should say to governments "Please provide your own list of which posts are misinformation, and we'll make sure that users see a blank page saying 'Your government has deemed this post to be misinformation' instead of the content they want".
You could do that, but the end results will be the same as the social media sites which don't do moderation.
They turn to shit, extremely fast.
It isn't there wasn't a lack of social platforms which didn't try to remove moderation "because of free speech" but they don't last long before they collapse under their own crazyness, and the crazyness of their users.
I don't think such a site would collapse. Instead, it would fragment into different bubbles, some of which would be toxic to mainstream users, but users wouldn't see any of that toxicity without specifically opting in to it.
I imagine such a platform would turn out like Reddit, only better, since people who opt out of the consensus reality would probably have their messages only visible to like-minded users, unlike on Reddit where each user is trusted by default in each subreddit.
