Interesting, that violates some of my assumptions. I think the basic model I'm suggesting might still be at play, though. I'm guessing most of those whatsapp groups are really big, so they effectively prevent people from insulating themselves from outrage if they just want to know whats happening. They can't just form a group with their friends and find other channels just to stay informed with minimal outrage and can't find news that's just straight news, the main source of news is the big viral firehose where outrage dominates. Does that seem accurate?
This conversation also speaks to the social complexity that gets obfuscated by some of these big platforms and the fact that things are different in all kinds of ways in different parts of the world. I don't know really anything about Brazil besides some fairly superficial basic history/culture and have pretty much zero contextual understanding of what it's like to live/communicate there. The fact that the same thing seems to be happening all over the world is really weird.
That's why I think it has a tight relationship to scale of communication channels, as that seems to be the main thing that's changed recently and is consistent regardless of specific platform/means of communication.