You can disable a Google Home device just as easily, and the rest of your comment is just you declaring by fiat that phones are OK because you personally find them useful, and the home devices are bad because you personally don't find them useful.

If someone finds their home device to be "more than a dumb box" and doesn't want to remove it from their life, you're at an impasse. No one granted you the authority to just decide where everyone else gets to draw their own personal line.