Full flow methalox for the new Raptor engines, stainless steel for the rocket body, the whole focus on full reuse (just the first stage for Falcon 9 but driving to the full stack in Starship). These are all basic things that nobody was doing before and now are being hurriedly copied as fast as can be done by competitors.

I'm most familiar with his SpaceX work, mind you, so there may be comparable decisions over at Tesla that are part of what put electric cars into the mainstream that I'm not familiar with off the top of my head.