Good point.

Many blogs like Zen Habits don't offer fostered conversations. Zen Habits doesn't even offer commenting, resulting in a subreddit with 6k subscribers: http://www.reddit.com/r/zenhabits (many of which links aren't from zenhabits). Lifehacker doesn't offer much fitness-related content (How can I bulk up quickly? etc). They tend to aggregate everything as well -> too much noise.