If there is one thing I wish I could beat into people's heads with a stick about online discourse, is that any place free of moderation is not going to be a free speech haven, but a cesspit where the people with the most free time will dominate and drive out others.
It's incredibly cheap and easy to shit up a conversation, but quite costly to have an engaging dialogue. By having no moderation, you're actively choosing to reward shitposters, and punish quality contributors.
And, no, adding an up/downvote mechanism does not solve this problem.