It's not only Twitter or politics. I've been playing some Heroes of the Storm as team building with my company and when we are not a full team the toxicity can get intense, with some people going far beyond just in match flaming to harassing with death and rape threats in direct messages long after the match is over.
Mind you this in a no-stakes free to play game and the phenomenon seems common. Sometimes I think our culture is not ready for a substantial part of our communication not to be face to face.