Actually, while I'm not sure exactly of how long the art of rotoscoping has been around, I do know it had been around for a long long time before it was employed in SW:ANH back in the 70's. (The original lighsaber special effect.) IIRC it was first made in the late nineteen-twenties.
I do know that not only in films but in photography this sort of collage or cut and paste refinishing has been employed many times. The effects took considerably more effort and care on the part of the manipulator. Back in the early daysone had to be particularly clever due to the lack of tools and resources in those times. Though in the B&W/grayscale era everything might also have been easier to change overall. So perhaps the difficulty is relative to the time and availability of things. As well as techniques originally used in the un-edited piece.
Yes I do suppose investigative tactics of testimony and words would yield better results.
Photographic manipulation now no longer requires much talent or ingenuity that it once did. Or having the great complex mind of old times. Probably why so much shoddy work to this end has surfaced lately as the ability to basically do this has become easier and more commonly available.
Indeed it is a powerful yet subtle form of deception. Or lately, advertising.