There's a use case for this: making an editorial comment to elaborate on the Hacker Newsiness of a general news story. For example, I just posted a story about Full Tilt Poker being accused of running a Ponzi scheme. It's notable that one of their founders was profiled in the New Yorker for his use of game theory to optimize his poker play (http://www.newyorker.com/reporting/2009/03/30/090330fa_fact_wilkinson is an abstract--the article itself is amazing.)
When I click on "Discuss," I don't get an option to add a comment elaborating on this. Is this a spam-protection mechanism, or something account-specific?