If someone makes an unsubstantiated claim, it is their responsibility to do the research and post the citation, not the 100,000 people reading the remark.
I'm pretty damn sure there's a fairly wide history of casual conversation not requiring footnotes. You know, among human beings. Also, primary research, opinions and soapbox ranting is perfectly fine in the real world. We're not living la vida Wikipedia and trying to write an encyclopedia here. We're nattering on about interesting, ephemeral topics.
I'll bet you're a blast at parties. "Hey, this is a pretty good beer." "Not NPOV! Citation needed!" Actually, having one guy become apoplectic in that manner at a party would be kind of fun to watch.
You're absolutely correct in the right context: my wife publishing a journal article has to provide citations. But Slashdot is not a academic journal, and is much closer to a bunch of people on a porch with a six pack. Social context: important!