Rank decay is not motivational to play ranked

No, but what has this anything to do with your idea being flawed. I understand your concern, but it’s just doesn’t make sense. It would be unfair, if you can come close (rank-wise) to players like Fan, who invest a lot of time to this game, while you don’t for whatever reason.

Otherwise we could just revamp the matchmaking, so everyone (across all ranks) get the chance you want. Why should players like you get a special treatment. That would mean ranking would need be overall easier and less of a grind, because that’s basically what you want a system that let you climb faster for half of the games.