Comment by robocat
10 hours ago
Your point makes no sense to me. A cable is often useful when WiFi isn't.
Case (A) is common for laptops. I've had plenty of WiFi modules (M.2?) go intermittent connection on friend's Windows laptops over time (maybe component drift?). For Linux on laptops I usually replace the manufacturers WiFi module so I get something better supported (high reliability - used to be Intel). Some people upgrade their module e.g. to get higher spec WiFi.
For (B), configuring WiFi routers is often easier with an Ethernet cable and sometimes necessary (depending on circumstances), and you need a cable to configure many other devices e.g. point-to-point links or whatever.
The fact you have a WiFi laptop is exactly why an adapter is really useful.
In my case, if I want ethernet it's because I want faster performance (reliably/continuously high bandwidth, and reduced latency and jitter) than my WiFi network can provide. But I've only been able to get that with a thunderbolt-connected ethernet adapter. Every USB one I've tried has been a disappointment.
I don't disagree that the uses you describe make them helpful in those circumstances, but I can't recall ever needing to do any of that myself. I'm happy with the built-in Wifi adapter and its drivers, and all modern routers can be configured/set up over WiFi, can't they? They create a default network when first turned on, or if you factory-reset them using the physical reset button.