I agree with what SquidVan said about this. The Master’s plan wasn’t “necessary” because humans were stuck in a perpetual dark age after the war. It was necessary because, in his opinion, human nature was the ultimate cause of the end of the world, and if humans don’t change then the world could and will end again. This fits with the theme of fallout, particularly the first game, that posits that humans are naturally violent and with large scale societies this only gets worse. It doesn’t have anything to do with rebuilding humanity. As you said before, humanity is rebuilding just fine considering the circumstances. That’s why I prefer the Master to the Enclave. He represents this pessimistic idea that really appealed to my edgy 11 year old self. Whereas the Enclave, to me, is a continuation of the idea put forth in subsequent games that the U.S. government was actually really competent and in control the entire time, they were just totally evil. I’d prefer to think they were just greedy, corrupt, and short sighted. It’s also why I’m not a huge fan of the vault experiments idea. It’s a cool conspiracy, sure, but I think it’s more likely that the vaults were more of a jobs program, a product of a bloated defense budget, and their failures were a result of cutting corners and general incompetence rather than some grand social experiment.