I don't think any of what you say particularly supports your final point. The internet is flooded in counterpoints, but few of them are on Wikipedia, or in Wikis. And none of them are as visible as Wikipedia's take on things. I think people are increasingly relying on Wikipedia to provide The Truth(tm) -- mostly because it's gotten so damn good at delivering it, the JFK examples notwithstanding.

Counterpoints seem to survive in ideological communities that have their own closed world view and their own knowledge databases which are considered to be definitive.