The OP uses the word "insane", not outlier. It's clickbaity, and used in jest, but I think it better captures a subtlety of this phenomenon: The prolific commenters are molding every discussion in their image. They might have an interesting angle on the story, or they might just be saying trivial things with beautiful prose. In any case, there is a lack of diversity in general -- discussions are driven by the worldview of a few.
That would be an argument for lurkers to make an effort, even if, like this comment, it's just a barely-formed idea.
Edit: "molding the discussion" -> "molding every discussion"
It's tough to get lurkers (like me) to speak up and shift the discussion when the emotional cost of doing so - arguing, being downvoted, getting defensive, being ridiculed - seems to make the effort simply not worthwhile for the individual. Not only on the web, but also in the office, at Thanksgiving dinner, at a cookout, etc.