What we wish champion rankings was
The idea is to show the skill someone has with a specific champion. Grinding points for a system that only illustrates how many times you played a champion is nonsense, literal nonsense.
The grading system should determine the rankings everyone sees, and should degrade both with time and with poor performance. It ought to be that when we see an S+ rating (or max rank, or w/e you want to call it) that we KNOW that person is really good with that champion.
What we really want is a system that tells ourselves and others how skillful we actually are with a champion. That would have been really cool. But instead Riot reinforces their system of all that matters is the win/loss grind fest. Sigh.