But I already have devices running linux-SBCs with "free" bluetooth in most rooms. Why should I need to add ESP32s just for that?

And what about the second-home-case I also mentioned?

Also, I use remote_homeassistant also for e.g HDMI-CEC-control of devices in other rooms/places, which ESPHome cannot do.

(I agree though, ESPhome@ESP32 is a viable solution for some subset of situations)