...in which case, bluetooth might stand a chance of working for tethering, as offered by the iPhone (btw, multiple devices can connect to a single tethering iphone with bluetooth concurrently)

IMO the lack of a WiFi AP mode for tethering on the iPhone is annoying. Bluetooth works fine for me but it feels very last decade.

One reason to use a cable is that you don't drain your phone battery - just your much bigger laptop battery.