It's important to the forum, given what we're trying to optimize for.
People often use the word "truth" (or "facts") as if it were a sort of trump card, but if you think about it, being true is neither a sufficient nor a necessary condition for a good comment - I wrote about this recently here: https://news.ycombinator.com/item?id=32697044.
There are infinitely many truths—they don't select themselves. People have to do that, and the selection process has to do with their own motivations, not truth.
Once you've selected a truth, there are infinitely many ways to express it—including how/whether you're going to take other people into account, how to encode your emotions in the expression, and so on. These also don't select themselves—you choose them, and again that has to do with your own motivations, not truth.
There is also the question of how perfect your access to the truth is, or to what extent you might be mistaken. Other people have very different ideas about the truth than you do (I don't mean you personally, of course). How lightly or tightly you hold that possibility is super important for conversation and again, has nothing to do with truth per se.