Man, it's been a long time since I posted in a Trek thread. I skimmed, I didn't see mention of this, so I'll offer it.
I don't remember how this fits into the timeline. But it seems to me, there's one single Trek technology that would pretty easily explain the whole thing. The replicator.
Think about it. Really. Forget about the logical improbabilities of such a device, forget about its surreality for a moment and let's do a thought experiment. Suppose for a moment that somebody invented a device that, with very limited energy input, could pretty much come up with any material you could possibly require. Food. Clothing. Building materials. Fuel. And a hell of a lot more.
Would war start to seem outdated? I mean, plenty of wars have religious and or racial and or cultural garnishes, but almost all of them come down to resource inequity in one way or another.
And think about capitalism for a moment. Would it still make sense? Provided you could use a replicator to create another replicator, what would happen to the haves and the have nots?
It's a silly little invention that isn't much mentioned. But I think its invention in this universe would have sparked a very different worldview. One where economics and national boundaries stopped making sense. Something that would pretty much level the playing field for humanity. And create a civilization where just kicking around as a starship captain without pay would actually make a lick of sense.