tl;dr This is exactly like Rousseau's Confessions except that I haven't peed in any kettles.
Anyway, I was the second answerer in @poolie's example, so here's what was up.
Oddly enough, I was trying to do the opposite of what you thought you were seeing (being competitive or ignoring the existing answer) by acknowledging the good answer that was already there. In that case, 'tshark' was, in my opinion, almost exactly as good as 'tcpdump' (which was the new info I provided), so I was also trying to give a thumbs up to that answer (as in, I, some other user with a reasonably high reputation, approve). And if you look at my edit, you'll see that I changed "tshark is fine" to "tshark is a good option" because I didn't want to give the impression that it was "merely" fine.
I have a lot of experience with packet capture software, going back before Ethereal/Wireshark was born. That experience was primarily with tcpdump, so I felt compelled to add that as an answer. It's still a good option, but not only have I used Wireshark more lately, but anything wireshark-related would possibly be a better option for a typical(?) askubuntu user. So I also added tshark and the apt-link to it.
There are definitely cases where I was feeling and possibly acting in a more competetive way. This happened to be a question where, ironically, my primary impulse was purely to add information I felt I knew something about (even though there was a very good answer present).
In my opinion, this means only that the example post you gave isn't a good one for your thesis, not that your thesis is wrong.
I'm sure that if I look back to when I first started on this site (waaaay back, less than three months ago), there are times when I didn't read the other answers completely. I know that I've looked at a couple of old ones where I had to thoroughly edit my answers because of some poor reading comprehension of both or either the question or existing answers. Sometimes I've given additional answers with only slight additional info, because it appeared to fill the dual purposes of being helpful and possibly getting me some upvote juice. Again, though, almost any answers I've given have the stress on the being helpful part. Most of my questionable but potentially helpful informational posting is done as comments these days.
To go farther than that, I expect I've posted several less than stellar answers. Some days, that's how I roll. My intention is generally to go back to them to make them better (or even awesome, comprehensive, and FAQ-like), but in some cases I haven't.
That's OK. If they suck, I expect they will be down-voted, and I'll notice this.
This is fine, and I won't take that personally. That's how the site works.
It probably means that my quality filter was broken when I posted, or that I mis-read or misunderstood something. I delete answers that I've made if they're completely wrong or broken.
Anyway, I don't expect that these kinds of behaviors are mine alone.
I would be shocked if they were.
The system here attracts people who want to be helpful, and keeps people who at least initially like the point and badge-bling system. People with varying degrees of altruism and greediness, or helpfulness or game-mindedness or competitiveness, come here and stay or leave.
I do notice that, lessening the impact of the competitive answer thing is the fact that I and many others seem to slow down with posting possibly competing answers after certain point boundaries.
For me, it's the same with editing. If I don't get hit by a bus, I'll eventually get the gold badge for editing stuff. But I'll continue to edit after that because I'm kind of OCD with some grammar and spelling mistakes, and because I want the site to be good, I want the answers to be helpful, and I want Ubuntu and this community to succeed.