Post-mortems are interesting.
My best guess is summer vacation :) it's at least true for my company who was one of the featured outages
TL;dr- complex systems are complex, and trying to understand them isn't usually possible for outside parties.
Bridges are also super handy for integrating with IRC, Slack and similar.
I've often experienced issues with sites that say "everything's sunshine and rainbows" on their status pages, only to find that many other customers are experiencing the same problem.
ex. After an earthquake affecting a large population, you'll see stories about other irrelevant earthquakes leading you to believe a frequency is higher and then that kind of headline dissipates but nothing has changed at all