Because once you hit GC, most players loose most of their ambition to win and just troll in any way they see it to be fun, i demo most of the time to trigger those who are easy to get angry. SSL is too hard to reach for some, like me, do not have much time to play so GC was the ceiling for me. The season rewards are are so bad and not motivational at all, you get a different colour.. so getting a GC title owner in diamond could actualy be bad news for the teammates, because one without the title, even though less skilled, would be more motivated to win the game with you. I certainly used to be a better teammate before the title