I'm curious about this too. There's also a physical connection between the joycons and tablet which can be used instead of the Bluetooth.
I believe the main issue is that it's very easy to electrically simulate button presses and be confident that the rest of the system is functioning correctly. Once you start simulating the entire controller and its protocol for communicating with the console, you start to enter a realm where it may be possible to trigger inputs that are not physically possible with the actual controller hardware.
I believe the main issue is that it's very easy to electrically simulate button presses and be confident that the rest of the system is functioning correctly. Once you start simulating the entire controller and its protocol for communicating with the console, you start to enter a realm where it may be possible to trigger inputs that are not physically possible with the actual controller hardware.