That's why Lionel Messi does not need any coaching. It's not like your advice is wrong it's just too simplistic. There are several reasons why a coach could be less accomplished than you and still be a great coach: 1) Provide a third-person , objective perspective on your performance. 2)Be a great motivator.3) Work like a resonance board to your ideas, plans. 4) Helping you to avoid mistakes they made. 5)More time to dedicate to specific pain points in your performance, etc. Grand-masters going to a World Chess championship assemble a team of other GMs, who are usually less (many times, a lot less) accomplished than them, but they bring a lot of good stuff to the table.