Well then maybe reddit should stop lying about what it stands for?
If it doesn't care about the principles of free speech (principles, not the amendment) then it should stop giving fake lip service to it.
Also, what you say isn't really true. 4chan does a good job of not censoring anything that isn't obviously illegal.
Any chat system built on top of the blockchain for that matter would actually be impossible to censor.
Or even just a simple email list, is in some sense an uncensored chat room.
Or text messages. Or phone calls.
All of these are in some sense, technology assisted chat services, run by private parties. And I'd describe them all as "bastions of free speech".
What if, to prevent harassment, your phone company listened to all of its customers phone calls and selective moderated them whenever you said a bad word? That is the equivalent.