Remember two weeks ago the Balance Team tried to ship us a Yasuo and Lee Sin buff? After a massive public outcry and dozens of topics questioning those "Buffs", the changes were eventually reviewed and stopped.
Now fast forward and the same situation is occurring but now with Yi and Rengar instead. Riot, if your listening, players have been complaining about the game having too much damage and assassins running rampant all year. Rather than buffing champions into more one-shot potentials, why not just reduce the damage of other high contenders? This isn't an arms race of making everyone OP.
Hopefully, if enough players are vocal enough about the team's actions lately change can start occurring :).