The IT guy walks in and replaces/restarts the box instead of waiting for the gods of AWS to descent to earth and restart theirs. They have direct control vs. waiting for something magic to happen.
The building has an onsite IT guy with enough spares to fix anything that could go wrong with the box?
You also have real-time ETAs from an actual human local to the issue. Plenty of domains where your clients won't care if AWS is down for everyone.