I would like to note that on what basis the automation is done is really sensitive whether indirect moderation is exercised. If you have categories or subject topics then a) it's hard to impossible to differentiate within a subject area b) the bonudary drawing is a moderation choice (ie who gets to suffer from their "neighbours" bad karma). Another naive failure mode is that if a user is as a whole bucketed as good or bad. This would misbehave if the person contributes to one area but gets really button pushed on another area.
And while it doesn't place that much limitations on the "free" part it might make limitations on the "speech" part. If you have multiple echo chambers that preach to the choir the cross-cultural interaction is missed out on even if cultural segregation is fully successful. That is while it would be text and there would be low amount of conflict based interruptions it would not be that communicative. In order to make transimission of information make sense you have to be able to send information that the receiver doesn't already have.