BLUF: The fact that nuking Japan wasn't necessary isn't some Russian propaganda, it was a sentiment strong even among many of the top brass of the military and Truman administration.
Not to start a whole debate on the utility of nuking Japanese civilians, but that "narrative" of the bombing being unjustified is nearly as old as the event itself, certainly not something that just became "popular in the last decade."
- Gen Eisenhower famously stated "It wasn’t necessary to hit them with that awful thing."
- Fleet Admiral Nimitz, Commander and Chief of the Pacific Fleet, stated "The Japanese had, in fact, already sued for peace. The atomic bomb played no decisive part, from a purely military point of view, in the defeat of Japan." (Though Nimitz's perspective is slightly diminished from reports that he initially supported using atomic weapons.)
- Major General Curtis LeMay, XXI Bomber Command (a unit of the Twentieth Air Force in the Mariana Islands for strategic bombing during World War II.), stated "The atomic bomb had nothing to do with the end of the war at all."
- Fleet Admiral William Halsey Jr, "The first atomic bomb was an unnecessary experiment ... It was a mistake to ever drop it ... [the scientists] had this toy and they wanted to try it out, so they dropped it."
Other high ranking officials like Fleet Admiral Leahy (Truman Chief of Staff), are on the record stating that nuking Japan wasn't necessary. Now maybe even given these perspectives, perhaps they are all wrong. What I can say for certain is that this perspective isn't without "any real rooting in primary source materials and is pushed on a speculative basis by fringe academics looking to make a name with an out-there theory."