Humans have been using emotions as part of rhetoric (that is, persuasive speech) since ancient times, and that's just the part of our existence we have written records for. I have every expectation humans evolved to be persuasive, hence our over-developed speech centers, and therefore have been using emotions to persuade since before humans as such even existed.
(Side note: "Rhetoric" isn't a dirty word, or at least it wasn't originally a dirty word. In the classical definition of the term, rhetoric based on facts and cool logic was also possible, and was also considered rhetoric. The modern usage of "rhetoric" to mean exclusively "empty" or purely emotional argumentation is not what the classical politicians meant by it, and not how the term is used in an academic context.)
Therefore, it's probably impossible to keep the heightened emotions out of debate without strict rules on content and participation. The extreme end of this is Usenet-style moderation, which means every comment to a forum ("newsgroup", or "group", in the Usenet parlance) is sent to a moderator's email address to be specifically (usually manually) approved, and no unapproved posts will appear in the group. That kind of moderation has existed since the 1980s, but to my knowledge, no modern web forum moderates that way. Take it as the far end of what's already been tried.
That kind of strict moderation can look like content-based or viewpoint-biased filtering (as in, all messages with a specific content or which take a specific viewpoint) due to a simple founder effect: If the few people who want to discuss this topic, or take this viewpoint, happen to be intemperate, they get moderated away, and it looks like that topic or viewpoint is being moderated away. The forum gets a reputation for that kind of filtering, and it can be very hard to shake it.
Now, are there topics or viewpoints which are inherently inflammatory? That's another question.