The reason the "famous or influential" are doing this is their voice/appearance/likeness is how they make their money.
If Youtube was suddenly flooded with AI videos of Jeff Geerling and Scarlett Johansson moving to Antarctica and starting a peach farm in a homemade bio-dome and asked for donations to keep the power on so they don't die, people may not believe it is fake ... I've watched stranger shows
This would have the real possibility of watering down their brand/image.
Taken a step further the "famous or influential" could be rendered unneeded, no pun intended, if they refused to appear in a movie and are simply CGI/AI inserted, appearance and voice included.