Facebook Accused of Watching Instagram Users Through Cameras
Don't want to be the devil's advocate here but just because camera is on doesn't mean anything is being recorded. As an iOS developer who worked with apps that access camera frequently, I can confidently say that it's just a UX optimization. Starting the camera takes a brief few hundred milliseconds which is easily noticable from a user perspective. By keeping the camera ready, they are making the experience smoother. I think this is it. Just because Facebook is an evil company doesn't mean this directly is a malicious move.