Balance
I bet that if there was only one item in the game and one champ, people would still complain about balance.
There is a thing called a skill cap for most champs. Sure some are lower than others, but some allow for amazing things.
So before you complain about a champ, check the skill cap.
Why is there next to nothing on Lee Sin but tons on Azir? the skill cap difference. Lee Sin can 100-0 people just like Azir. But when Azir does it, people spam the fuck out of the boards.