I don't completely agree, good quality photo editing, even in this day and age, is not that mainstream. You need a decent amount of skill to edit a good quality picture in a way that won't look obviously fake. Pre-digital-photography it was only possible for skilled people with a significant amount of resources (like the Soviet government, no doubt).

Besides it's one thing to edit a still image and a whole other to forge a long video, complete with audio. Look at those movies these past few years using 3D models to insert younger versions of actors (Terminator and Star Wars come to mind). They must have invested millions into it, they have very talented artists and it's pretty good but it's still quite easy to spot the fakeness of it.

Pre-digital it may have been destined for old-school newspaper pictures with the varying density dots - monochrome of course. That would mask a multitude of sins and shoddy brushwork.

The Daily Mail was at it from around WW1, perhaps earlier. Though their main WW1 fake was, of course, the cadaver factories. Surprisingly the Times bought that tale too.