[ticksoft]

At some point those vote-driven-websites are expected to mature and turn into proper publishing businesses.

Anything that's driven by users rather than vetted and sanitised by trusted writers/editors, will scare lucrative brand based advertisers. Just look at Google Adsense's content rules to see how much advertising shapes the web's content.

I think that's what happened with Digg. I speculate that something similar is happening with Reddit but at a much slower rate - like closing undesirable sub-reddits etc.