This may have been the case a while ago with local radio and non-cloud based services running devices but things have changed. It seems like most modern devices end up "phoning home" to a centralized service. This is why Roombas had a problem vacuuming when there was an AWS outage the other day.

I'd prefer that devices talked locally to avoid concerns about data privacy and it may allow for better local coordination between devices. However, it seems that most orgs are building bigger fiefdoms with a bit of coordination through groups like Matter.