I don't think this is a fair analysis at all. Everything about Nier Automata came from Platinum. They were the developer and many talented people worked on it. Yes, Yoko Taro is the director and it is his creative vision - but creative vision alone does not make a great game. Interactive entertainment has a ton of moving pieces. Why is Nier Automata the only Yoko Taro game to be so successful after he had directed 3 Drakengard games and a Nier game before that (2 versions of it even!)? Because it is by far the most polished execution and presentation of Yoko Taro's ideas - because the game runs well, looks good, controls well, plays well, and has a great UI.
You can have a great script for a movie, and it wouldn't engage a ton of people if you end up with a poor cast, sloppy production design, lame sets, weak cinematography, etc. Yoko Taro has really good ideas, but Nier Automata is the first game he directed where he was paired with a developer who could elevate his concepts and ideas into a cohesive package that felt complete and satisfying in a way his previous games didn't. All that credit is owed to Platinum. Not just "the combat system." The programmers, the art team, the animators, the game designers, etc. Every single person who worked on the game contributed to making the game stand above all his previous games - and the majority of them were Platinum employees. Let's not sell them short.