Why are “smart homes” always presented as either all in or all out? We have a handful of Wemo switches that we use to turn on various lights, mostly on a sunri

Why are “smart homes” always presented as either all in or all out? We have a handful of Wemo switches that we use to turn on various lights, mostly on a sunrise/sunset schedule. They are reasonably reliable with no more than about 1 failure to switch in a month. My husband sometimes needs to repeat himself if he is using voice commands but then, he is a mumbler and I often have to ask him to repeat what he says to me. If I needed to switch one without voice or app, I can just tap the physical button on the switch. When we leave town, they continue to switch off/on. I no longer have to dig out one of those Daisey-wheel timers and try to figure out what is on and what is off. None of these lights are ‘critical’ in that, if they don’t switch now and then, I’m not upset. I don’t demand 100% uptime for decades at a time. At worst, I might have to unplug and replug in the switch to reset it. I don’t try to get complicated with them and have no particular desire to automate the rest of the house. I feel like my home is smart enough at this level, not particularly fussy, and not a source of stress.