I think the webcam light is completely controlled by the hardware signal, so the only way to turn that light on/off is by turning on the webcam itself, which I don't think is desired either.
All Apple computers since ~2009 have had the webcam light on the same physical circuit as the webcam, such that one can not be powered up independently of the other.
PCs and third-party webcams are of course another matter...
https://www.washingtonpost.com/news/the-switch/wp/2013/12/18...