A Scrum Master working at a team level should have facilitation skills and generally have the same skills as an RTE, but empowering a team of 100/150 people and making those people feel like a part of the one train is a different story. And the ultimate effort is directed towards making this a reality, creating a psychologically safe environment, mutual trust. ART should be seen as a single body, not as a group of competing teams, and the focus is on helping them reach this excellence.
It is not easy to find someone with all these skills and all the different aspects, but usually, a few people can be the right hand and act as a shoulder of the RTE.