When I was looking at home automation systems and all the insanity found there. at one point I said "if I were to design a home automation system from scratch what would it look like?" my answer for the physical layer was poe and managed switches.
As somebody that's looked into this... yes, but. The contemporary light switch is instant. Within a few nanoseconds of your brain feeling the "click", you see the light. There's a noticeable latency from an API request to the switch's control plane which then talks to the power control which then turns power to the port off and then the light goes out. You have the additional delay of poe negotiation for the "turn on" operation, too.
Which is still ‘instant’, but with some non-ridiculous implementation, also easy to do with a ‘smart home’.
Of course most implementations are pretty ridiculous, so there does that idea.