I'd like to offer a counterpoint to your critique of Slashdot's moderation system....
My time is limited. I hardly ever want to read all ~50 comments on a story. That's where moderation comes in handy: filter out all the low-point comments and boom! I can get the gist of the comments in just a couple minutes.
I'll even go a step further and say that often, group-think is useful! Consider a non-techy person such as myself: A story about some new piece of hardware or a new scientific discovery, usually has comments that cut through the PR BS and give the straight dope.
The fact that Slashdot stereotypically attracts a smarter-than-average crowd is why I'm here.
There is a lot of cynicism in this thread about "brigade modding." But more often than not, if a comment has been moderated to +5 Insightful, it usually is.
I don't know. Just my two cents.