I think it really comes down to mechanics at that rank. Someone who is even slightly capable of higher level mechanics is going to absolutely destroy someone low ranked without both the knowledge of how to perform the mechanics and how to defend against them.
Then you hit champ and it's the same thing, except the advantage is in the hands of those who have perfected the mechanics.
honestly at champ level it's not about the mechanical advantage. It's tighter/faster rotations and positional awareness/game sense that is heavily increased.
and someone mechanics but not anywhere near as impacting as the above.