I wrote the enigma/harbleu interview article, and before that I was an amateur games journalist reviewing games and writing about game design.
reilly makes an excellent point about one type of journalism; reporting. The other hand is editorials.
The reason that there aren't upfrags and downfrags on articles, at least in my interpretation, is that up/downfrags are used to validate an opinion. An inflammatory comment would receive downfrags (ideally) and a well-spoken, fact-driven comment would receive upfrags. Since all the article writers are curated to a decent extent (through enigma), all of them are held to a journalistic standard (which is not to be inflammatory, be informative, and be fact-driven), thus it's far more useful to communicate with the article writer through comments (and/or discussion with others!) rather than through up/downfrags.
Plus, it's awesome to see your own article with lots of congratulatory comments AND upfrags on those. It's the best. <3