I’m talking about cases where the broadband is the bottleneck, obviously. These are people who do not own a microwave or TV (they’re lucky to have a flush toil

I’m talking about cases where the broadband is the bottleneck, obviously. These are people who do not own a microwave or TV (they’re lucky to have a flush toilet) and their nearest neighbor is far enough away that the neighbor’s WiFi is undetectable, so the issues you mention do not apply. Yet they are told by an installer who does a physical visit to the place to put in a dish that choosing the 5GHz WiFi will make a difference. It won’t.