This is not true. Look into Zigbee binding, it works when the coordinator is offline.
I'm using that as a backup solution in my house. All lights are zigbee, permanently powered, normally most are controlled automatically by presence sensors. But I have a couple of Zigbee remotes in a box that are bound directly to the lights to use in case my home automation system is down.
Hue light switches (well, the ones I have) simply stick on the wall with no wiring.
The _real_ light switch is permanently on, and the _hue_ light switch sends a beacon to the hub to turn the configured lights on/off (the light bulb socket is always-on)
No, some switchers and dimmers can also control lights without a hub present. Some products come as a paired bulb and switch, with only an optional suggestion that you later extend into the ecosystem.
I'm using that as a backup solution in my house. All lights are zigbee, permanently powered, normally most are controlled automatically by presence sensors. But I have a couple of Zigbee remotes in a box that are bound directly to the lights to use in case my home automation system is down.