> That's a critical part of having a trust value within a social network and if moderators of a popular sub don't think a poster is meeting the bar to post it is good for them to ban it and become higher trust. If they go too far than there won't be content on the sub at all though.

That's implying that there is a single one-dimensional quality metric. The problem is when moderators of popular subreddits (for a particular niche) or those with the most obvious names for a particular topic start to enforcing their own personal biases in the discussion rather than sticking to keeping the discussion on-topic.