League is meant to be unbalanced
every class of champion will go through their phase of being op, it just rotates, Tank meta, adc meta, assassin meta, supports. its to keep people playing, to feel like the game is "evolving," and to keep people coming back to it, riot 100% make certain champs OP so you can buy their skins,
after all riot is a business and they need to make money off the game
think about if the game was 100% Balance people would get bored, and go play some other game, they would not spend money on it.