About nerfing champion

Hi, everyone and Riot staff. i am one of those who loves playing league of legends. it is a really interesting and attractive game. i only played it for a year and have seen so many "op" champions in the game get nerfed and disappeared. Well, for the balance of the game, nerfing is a method. However, it does not work very well in some cases. Except some champions, for example, Kassadin. He is weak in the early game, so it is fair enough to give him strength in the late game. i mean this is Kassadin's job and his characteritics. Many players try to find some strategies for their favorite champions and they played some games and get 10 kills or 20 kills, then some other players said, "they are op, we'd better nerf him"As you guys expect, he got nerf, and the players who loves playing or develops strategies for this champion will be upset. Each path will make some champions become "God" and players keep playing them or they are forcing to play them because if they are not playing them, they will lose the game.You can see it a lot in rank game. This situation will seriously reduce the diversity of champions. I suggests, instead of nerfing, Riot can boost many other champions. If every champions are op, then losing the lane or game is players' problems. i love this game, and i watch LCS a lot, but it's pretty sad that only few champions are on the stage. the reason is that they are op and others are not. i really want to see more champions in the game and more strategies. I believe this game will be better. It is just my personal opinion, what about you guys? what do you think can make lol live longer? （btw my English is not very good, plz don't blame me on my grammatical errors)