There are powerful champions in league, everyone knows this. But when anyone posts anything about there being a champion that is used in like 50% of all games, or that shuts down an entire team, they get flamed. Everyone knows that every champion has their spotlight at overpoweredness. Jax was underpowered, no changes made to him, then one day the meta changed and suddenly Jax was unstoppable. What happened? People posted hundreds of forum posts and then Riot nerfed Jax. (A little too much IMO) but the point is, these posts help balance the game. There are over 100 champions in league, do you think it is possible to balance all 100 around each other? NO, so each champion will go in and out of power and people just saying L2P noob obviously have not played this game long enough. Champions right now that can change the entire outcome of a game include blitz and malphite. Why? Well Malphite is ultra tanky, has an AOE CC that does decent damage, can almost always win lane if good, and shuts down nearly any AD. Sooner or later he will fall out of power. Now blitz, his grab range is the highest in game, not to mention it pulls a champion back that range too. Just him being in the game changes the enemy team playstyle. If he's near, noone is going to want to get close. He has 3 CC mechanics and a speed boost to catch people, not only that but a shield for tankiness. If he lands a Q, it is instant death, put that in a teamfight an he's a support that guarantees a kill. Put that in lane and he basically forces the team's ADC to get fed. Even in a lane of 2v2, a Blitz Q-E-R will CC a person long enough for the fight to already be won. These are my opinons.
But we also have to remember this. Just because it isn't this way in high elo games, does not mean it's not a problem. League of Legends has over 8 million unique players each month. Maybe 10% of them play ranked competitively. The game should be balanced around unranked gameplay just as it should ranked. I don't consider myself bad, i play ranked very rarely, but I have 1100+ wins and around 100 more wins than losses. I have a friend who nonstop watches ranked videos and tries to apply them to a normal game and because of this, he makes mistakes. High Elo gameplay is far more different than Normals. So don't say because this champion is not top tier or this champion isn't banned, they aren't OP. There are so many factors. Maybe you do play ranked and you see a normal player complaining about a champion not picked in Ranked, don't flame, they have a different gamestyle to deal with. Maybe you are a normal player and you see a ranked complaining about a champion that isn't even used much in normals, yet again, different game.