However, the problem is Spock commits it by calling the Eugenics Wars "the last of your so-called world wars". And by saying "the last of it", implies WW3. He calls it both a world war and the last of them.
Yeah, they changed it. But it was a change that made sense at the time. In 1967, the 1990s seemed like the remote future. But in 1987, that wouldn't wash anymore, so it made sense to retcon the timeframe of the global war to something more comfortably distant. Honestly, I find it strange that later Trek productions
during and after the 1990s were so literal-minded about past canon that they felt the need to re-establish the same Eugenics Wars dates that "Space Seed" had used, rather than updating the timeline to something more plausible to modern audiences, as other series such as Marvel have done with their timelines.
The idea that such a war may not affect the USA and the idea that it may not even report it much in the media much just doesn't sound very plausible. A small scale war yes, understandable.
Okay, then how much can you tell me about the Sierra Leone Civil War, or the Algerian Civil War, or the Burundian Civil War, or the First and Second Congo Wars, or the other African wars of the '90s that killed tens of millions of people? That's hardly small-scale.
And again --
none of the wars in the 20th century, not even the World Wars
, had any combat on American soil. Our cities were untouched by the conflicts, except for things like rationing, scrap drives, and propaganda. If Los Angeles remained intact throughout WWI, WWII, Korea, Vietnam, etc., then it's not even slightly implausible that it was intact during the Eugenics Wars.
With 79 episodes of a weekly series that you have to wait for re runs to see again maintaining a basic integrity is not too difficult.
Or rather, it wasn't too important. Because of the lack of home video and such, there was no guarantee that a given viewer would ever get to see every episode of a series, so the priority was to make every one self-contained and complete with no dependence on any other episode. Plenty of shows in the '60s and '70s had little to no continuity and aspired to an anthology-like approach. Creating a sense of a consistent universe was a low priority, because it was harder to experience a series as a continuous whole than as a series of isolated segments.
And even worse - licensing agreements that insist that a certain percent of the show needs to be different are frankly insane when dealing with a long term franchise and large fan base.
I'm pretty sure that's a myth from those disreputable Midnight's Edge videos.
Discovery is made by CBS, the company that out-and-out
owns Star Trek. No "licensing agreements" of any kind are involved, because the owners don't need a license to use their own property. And we saw that
Discovery directly incorporated footage from "The Cage" into
If Memory Serves, so clearly they are free to use the original material.