Seems like there was some innovation going on with SpaceX (though Musk had absolutely nothing to do with it). E.g. they used existing technologies, but some of the tech apparently hadn’t been used in rockets before. From what I’ve read, some of what they used was apparently fairly expensive - it hadn’t been used before because it was seen as over-engineered for purpose, but it allowed SpaceX to make the rockets robust enough for reuse.
But yeah, that too.
