A couple hypotheticals here:
A way to overvoltage/current and burn out the LED. Probability low, but nonzero.
More plausible situation: There are times when the camera is pointed at me, but my head is not pointed at the camera. Perhaps I left the laptop on in the corner of a room while it's playing music, or a myriad of other things.
A cover is a simple, foolproof solution to the camera issue.