The computer can't detect if I have a working and available input device connected - the fact that some devices claim to be connected doesn't imply that, as it may be damaged, a virtual device, or not wirelessly connected but simply listening for a possible connection that may appear at any time.
For example, right now I have a mouse and a keyboard connected, but Windows device manager somehow shows 5 keyboard devices and 4 mouse devices due to various connection drivers listening to devices that might be connected but currently are not. If I came home after a long vacation and found out that the batteries in them are dry, then there would still be multiple devices of the same type "available" when I'd try to connect a wired USB keyboard.
If I want to connect an input device, it is quite possible that the only way that I could allow or disallow anything is through that device itself.
The computer can't detect if I have a working and available input device connected - the fact that some devices claim to be connected doesn't imply that, as it may be damaged, a virtual device, or not wirelessly connected but simply listening for a possible connection that may appear at any time.
For example, right now I have a mouse and a keyboard connected, but Windows device manager somehow shows 5 keyboard devices and 4 mouse devices due to various connection drivers listening to devices that might be connected but currently are not. If I came home after a long vacation and found out that the batteries in them are dry, then there would still be multiple devices of the same type "available" when I'd try to connect a wired USB keyboard.
If I want to connect an input device, it is quite possible that the only way that I could allow or disallow anything is through that device itself.