I think the difference between Reddit and 8chan, the difference, is the lack of a voting system. Consider that Reddit, after any post has three more downvotes than upvotes (score of -2), by default, that post will be hidden. Most Reddit users browse not logged in (according to their own stats), and of those that are, most have this "threshold" option still turned on, and it leads to more echo chambering since views that are unpopular will simply go unseen. Another plague is that people will go through your comment history and attempt to use that to discredit you.

On any *chan style imageboard, this isn't a thing. You can hide posts that you don't like, but by design, all posts are equal. If someone posts something you don't like, your options are to ignore it or respond to it, but it's there, in the open, for all to see.

This, I think, is the better system, combined with the default anonymous posting style of these boards that completely ensures that any post is judged on its merits, rather than the identity of its poster. That's not say that board culture doesn't exist, it does, but it exists purely socially, rather than being a feature of the software. The things I've seen happening on YouTube and G+ and Facebook have convinced me that existence of a coherent identity has zero impact on people's behavior.