Why do we do this? It doesn't work.
You can't have a balanced game if you nerf or intentionally keep champs weak just to appease your worst players.
The answer to a Bronze player complaining about Garen or Yorick is telling them how to improve against them; they should be incentivized to be better until they are not a problem to the player anymore. Rewarding their complaints with nerfs only keeps them in Bronze; they have learned nothing, those champion's will probably still stomp them, but now they're dramatically worsened higher up the ladder.
Lets put a cap on this.