That's half the equation. The other half is the reliability and security of wifi, which is less than that of ethernet for people without physical access to my wall innards

On the other hand, _all_ the WiFi devices that I had at some point fell off the network, at least once. Including doorbells and cameras. While PoE devices just work.

Another point is that mains power in my area can go down periodically. My PoE switch is powered by a Li-Ion UPS and can provide power for about a day.