If competitive popularity is the only factor when balancing a champion, this game will be destroyed.
Why should champions that do well competitively have to be nerfed every time? Is there not one Rioter that says "Hey, even though this champion has won 3 out of 3 games in the LCS, it's okay because they were never counterpicked. They are not actually OP."
This is the same principle with the ranking system. Jeez, you're bronze? Wow, you must SUCK!
You're Diamond, you're REALLY GOOD!
I've met my fair share of crappy Diamonds and I myself am an above average Bronze player. Understand this: It doesn't matter what your rank is, it will NOT decide how well you can play your favorite champions.
But Riot continues to support said ranking system instead of working hard to define one that would actually properly suit a game like this.
You see Bjergsen on leblanc? He counterpicks Ziggs and other mid champions. Should Leblanc get nerfed for being played at a high level, and when she is not counterpicked? So she can do worse when she is countering, and do even worse when she IS countered? Where is the logic in this?
Sometimes, professional players bring things to light that should have been shown ages ago, like Mundo's cleaver being way too easy to hit (it is also very difficult to see). This was nerfed and this is a good thing. But things like this are completely unrelated to the fact that Riot likes to nerf champions just because they are popular and/or SEEM OP when they actually are not.
Riot wanted to reduce Zed's split pushing power. So instead of reducing the damage he does to minions they reduce the damage he does to EVERYBODY. Reduce his shuriken's pass-through damage to punish him for landing multiple champions in a skillful play instead of reducing the damage his Q does to minions. Increase the cooldown on his E (this has done personally horrible things to me, just for the record) because he clears too fast - instead of reducing the damage his E does to minions. And let's put in a nerf to his shadow speed (which ALSO did numerous terrible things to me) to reduce his impressiveness, make him feel incomplete, and best of all, bug it so even though you dash out of a nami bubble at the last split second, it STILL stuns you even though you CLEARLY dashed out of it.
Zed is the most counterable asssassin in the entire game; yet also the most nerfed with the most stupid balance changes. Hey guys, reducing damage to minions is an actual mechanic, you know. Let's apply it when it's needed instead of butchering champions.