I’m not who you’re replying to, but in my case the hub being unavailable should mean everything can still work as normal. For a lot of smart bulbs, a busted hub means you can only control them by switching them off then back on since you were relying on the hub to control them.
Some switches allow for direct control of zigbee or zwave smart bulbs so even if the hub is non functional, a press of the switch will still toggle or even dim them.
I totally agree with your principle about fail normal, but how is this a violation to that?