Part of it is the paranoia about what people perceive as trolls or shills, combined with thinking that their opinions are a matter of life and death. I've seen people here talk about the old internet and I think what helped back then were communities were generally smaller, more tight-knit, and there was a greater separation between the internet and "real life". I can't fault people for being paranoid when many governments and corporations have added the internet as a platform where messaging must be controlled.
There have been media works that point out that the internet, although allowing people to connect from all the way around the world, paradoxically isolates us. This is something we can at least partially mitigate by giving others the benefit of the doubt and not be so quick to dismiss and antagonize. While it is tough to respond kindly to someone who insults you, sometimes doing so can have a disarming effect on them.