Reddit is not a nonprofit Free Speech machine. It's a business. So, yes, the emotional state of the listener -- in so far as that emotional state (positive or negative) is a determiner of traffic and therefore returns for investors -- is the responsiblity of the speaker (the website itself).
I thought by now we had shed our idealism about platforms and corporations. We've mocked Google's now-defunct "Don't Be Evil" for years. The idea that Facebook is just a way for distant friends to stay connected has been subsumed by the reality that it's actually a privacy nightmare. But the myth that Reddit exists as a bastion of free speech at all costs has somehow held firm. It's puzzling.