The simple fact about the internet is that *many* people "log in" just to vent and blow off steam, regardless of a website or app's topic.
I have seen delirious flame wars in the CityData forums, I've seen them in mushroom-hunting forums, I've seen them everywhere -- because a large percentage of people are just logging in to raise hell, get angry, and start lobbing stones at anyone and everyone to "de-stress" during or after the workday.
At this point, just expect "the worst in people" online, always. That's the default. Anything actually wholesome and nice is just an unexpected perk.