>Before SpaceX started to do it, the concept of iterating to that degree on rockets was unthinkable.

I'm pretty sure that was what NASA was going to do all the way back in the 70s before their funding got slashed. It was a novel idea but not a novel idea that SpaceX was particularly responsible for, just one they threw capital at because the government stopped caring after the space race.

Nuclear power research, by contrast, never really suffered from a lack of available funds. They were throwing money at mini reactors back in the 90s, saying all the same stuff about how mass production would bring down the price.