It's not "off" unless you're simply reading it literally. If you do that, then it's a verbose way of saying "I agree". But the connotations are something like "I agree, strongly, and in particular am implying (possibly just for effect) that there are objectively right and wrong answers to this question and the other answers are wrong." The main difference is the statement that there is an objective answer to what people may be treating as a subjective question.
If it helps, you can think of it as saying more about possible disagreeing opinions than about the specific opinion expressed. "This answer is right, and the people who disagree are 'objectively' wrong."
It took me some time to catch on to this. It can certainly be jarring or obnoxious, though sometimes it can be helpful to say "yo people, you're treating this like a subjective opinion, but there are objective reasons to conclude X."
I (the comment writer), agree that it's jarring and a bit obnoxious. There were three factors that led me to write it anyway, which I've mentioned here:
Edit: Rereading the comments, I agree (heheh) with you analysis. I hadn't considered saying "I agree", because I didn't feel I was expressing an opinion, but a fact, like 1+1=2. The comment stated that the mods in fact disallow those comments and provided proof, so I didn't consider it an opinion.
Heh, and rereading my comment, it comes across as more against the usage than I actually feel. It's not my personal style, and sometimes I find it annoying, but 80% of the time I think it's totally fine and expresses a nuance that would take a lot more words otherwise. Your usage here, for example, seems totally appropriate to me.
The reason why I was reticent to use it was not because I was uncomfortable asserting an absolute (the link showed clearly that mods didn't allow these comments, I don't see any controversy there), but more so that on this type of forum, the act of voting itself is the primary method of agreement. Saying "I agree" or "this is true" or "THIS!" is generally redundant and noisy.
I really like this conversation by the way. I'm actively trying to become a better writer (by doing copywork of my favourite writers), and no other forum on Earth has this sort of conversation in such an interesting, nuanced way.
If it helps, you can think of it as saying more about possible disagreeing opinions than about the specific opinion expressed. "This answer is right, and the people who disagree are 'objectively' wrong."
It took me some time to catch on to this. It can certainly be jarring or obnoxious, though sometimes it can be helpful to say "yo people, you're treating this like a subjective opinion, but there are objective reasons to conclude X."