Late game champs tha aren't team dependent are unfun for both teams. (Looking at you, Yi)

Late game Champions by design drag their team down until late game. This is okay so as long as they are team dependent, as when late game comes every player still feels like they can work as team to win, for example Kog'Maw has a notoriously bad early game, but come mid and late game his team knows that if they work to keep him alive they can win fights, even if they lost the early game. But when a champion is strong late game without being teamwork dependent, everyone suffers, especially their teammates.

The champion's team suffer early game because of the late game power budget, but come late game they still feel worthless as they are relying on their late game ally without having any clear way to help them, while the opponents have to deal with target who needed to be so overloaded come late game in order compensate for how hard he screwed his team.

This is especially true in the Jungle, as the Jungle exerts the most influence onto his team as a whole. A late game team dependent jungler is can be healthy and fun to play with. When you have a Warwick on your team, you know you are going to suffer early game, but that's okay because you know once he has is ultimate you can coordinate with him to shut down that lead your opponents got on you early.

Yi on the other hand, is extremely unfun to play with. You know if their jungler is any good, you will suffer for Yi's early game hard, and will never be able to recover personally. Come Sated, Yi is suddenly an unstoppable menace, but as a lanner, about the most you can do to help him is get dove under tower and die for him to clean up after. Congratulations, your entire team is behind, and is now entirely dependent on Yi's performance, without having any real way to influence it.

How is this fun for 9 out of the 10 players in the game.