A well-designed home automation system will still work with manual controls and/or if the system is offline.
I have smart devices everywhere yet I can still adjust the thermostat manually, turn on lights using a normal switch, set the house alarm using the keypad etc. However, I also have a 'Night' scene in Home Assistant which sets my alarm to night mode, turns off all the lights in the house and sets the thermostat to night temperature all with a single tap and all over the local network.
^ this. You need to have a high WAF - wife acceptance factor. Another analogy is that grandma needs to be able to stay in the house and not need a computer science degree.
Your home automation system is a complimentary enhancement to a traditional, switch-on-the-wall and physical TV remote control set up.
I have smart devices everywhere yet I can still adjust the thermostat manually, turn on lights using a normal switch, set the house alarm using the keypad etc. However, I also have a 'Night' scene in Home Assistant which sets my alarm to night mode, turns off all the lights in the house and sets the thermostat to night temperature all with a single tap and all over the local network.