Paid members can ban people from threads they create and are immune from other bans. Post there long enough and you'll get banned either "randomly" (all available evidence points to the random bans really being an attempt to extort money for paid memberships) or because you posted a link to a different website off some secret banned list.
This is a trend with electronic media that has me worried. Rather than expose themselves to a diverse range of viewpoints, people often form insular "echo chambers" and actively isolate themselves from those they disagree with. E.g., on Facebook it seems common to "friend" a lot of former colleagues and school classmates, distant family members and the like, only to quickly defriend them when a heated (usually political) argument develops. Then everyone is left talking only to like-minded people. You even see them developing their own distinctive language and culture, as isolated groups always do. E.g., hoaxers using "LEM" instead of "LM".
Computers are just tools, and it's vital that their end users always remain in control. You obviously can't
force anyone to talk to anyone, and even the most open-minded people still need "defriend" and "ban" mechanisms to deal with outright spam, abuse and the like. So this is a people problem, and I don't know what to do about it. I'm an engineer, not a sociologist.
Computers do introduce some new social problems of their own, such as the well-known lack of tonal inflection in written text. Key & Peele did a sketch recently that illustrates this problem beautifully (and hilariously):