" I was hoping for (and got) intelligent, measured discussion"
the line between this and "argument" (used in the debating sense, not in the shout at each other sense) is very thin. The word to focus on is "provoke" not "argument". What makes it "argument" is that by setting up artificial poles opposed to each other simultaneously you are attempting a combative argument vs an exploratory one. That it didn't turn out that way is due to the strength of the HN community, which largely didn't take the bait. But bait in the water, there certainly was.
This is (imo) abuse of the system. Just do a thought experiment and imagine people submitting all kinds of paired posts (like you did) to get "intelligent measured responses" to their own questions - "Emacs is better than Vim"/ "Vim is better than Emacs", say. "Measured responses", sure!
HN would go to hell very fast if everone started looking for "measured responses" in this fashion. Quoting allenbrunson , "I'm just noting that this is a clever hack that illustrates a problem in the system.". It is clever. and it is abuse in that it takes advantage of a vulnerability in the system.
"I felt (and still believe) there would have been less discussion without both articles being posted."
yes this is the hack bit. And it works (as long as it is just the odd person doing this). Jumping a red light "works" too, if reducing the length of your trip is the only criterion.
"FAR more interesting than me typing up a summary of both arguments and submitting that instead, as you suggested in an earlier comment."
In other words you don't want to do any work up front but do want get people to argue each side of artificially paired posts. Hence the word "provoke".
As Allen said above, "if this hack started becoming common, I'm sure the editors would eventually put a stop to it."
In other words, it is only the rarity and novelty of this tactic that stops you from getting stomped on.
All that said, do what you will! If such abuse continues and spreads, the moderators will land on it with both feet.
Or you may indeed have found a superior method of topic submission and I am completely off base, in which case I'd expect the other participants on HN to copy your superior style of topic submission.
Signing off this thread,