This makes me wonder if part of the problem is that it’s a bit like the psychology of road rage. It isn’t so much the trigger, as it is that it happened in an perceived personal safe space. Maybe It’s not that there’s someone wrong on the internet that makes people angry, but that the comment was fed to them while they were reading things they like. Something with a blended approach that makes it clear when you’re leaving the bubble and might be more tolerable. Like turning on PVP in a mmorpg, you expect to encounter opposition.
Yes, I think there's part of that. In the same direction, compartmenting to have some stuff come within the frame you expect them might help a lot.
Google's defunct social network tried to embrace that concept to a point, and facebook also has some way to create explicit bubbles, but I think your vision of visually separate modes when moving between contexts coud be the best approach.
