I'm not sure real "jerking face" blackmail is that frequent. If caught the author would face heavy charges. It's probably way easier and less risky to massively scam by pretending you had access to the webcam than to actually bother to hack.

Beside I'm not sure a "jerking face" would be more than awkward if published. A reverse angle in which you could identify what was the video used for the jerking session would be way more compromising.

And in this regard poorly protected IOT surveillance cameras have way more evil potential that webcam in my opinion.