The moderation is just that the barrier is in a different place, and it's hidden for the most part. But there is moderation.
It's like the pub you don't want to drink in because it's full of the thugs and drug dealers who have the scariest bouncers at the door. Any trouble makers get taken out back, but they do have methods to control what they consider to be trouble makers.
We know 4chan is moderated, simply because 8chan exists and has produced several more mass murderers than 4chan has, despite the close overlap of ideologies. 4chan has a magnitude less users posting their manifestos before committing mass murder.
The moderation is just that the barrier is in a different place, and it's hidden for the most part. But there is moderation.
It's like the pub you don't want to drink in because it's full of the thugs and drug dealers who have the scariest bouncers at the door. Any trouble makers get taken out back, but they do have methods to control what they consider to be trouble makers.