The problem isn't that people want champions to be a certain way.
The issue is that League is a competitive game, and people want to win often just as much if not more than they want to have fun (because let's be honest, how much fun is it to lose usually?) What happens is that people are always looking for new champion builds, but often it's not just for fun, but because they want to find the most broken and obnoxious means of combating opponents.
I'll use tank Ekko as an example, people's problem with tank Ekko wasn't that he did damage while building tanky, because that would be what a juggernaut is supposed to do.
But Ekko doesn't play like a juggernaut.
He plays like what he is when he builds tanky: a utility assassin who is oppressively able to stick onto targets and melee them with percent maximum health, and able to disengage just as easily, he simply trades outright burst for being able to have the health pool to back up his ability to disengage. Thus, you end up in a situation where the only way to beat tank Ekko is simply to not fight tank Ekko, because if you fight him he will get onto you and even if you concentrate everything you have on him, he can just ult out; and you can't just ignore a tank Ekko because he's trying to get onto all of your squishies like a traditional tank, letting him get his way is bad.
Basically it becomes an issue where there is no way to beat a champion short of banning them in the champion select.
And that is the problem there: people are trying to find ways to basically make it so their opponents can't win, because they usually win if their opponent's can't beat you.
All these oppressive builds, people's issue with them is that said playstyles are obnoxious and have little means to be beaten outside of banning a champion or forming a team specially to counter said champion. It's the same reason people find certain champions obnoxious like Zed and Fizz, and playstyles that make certain champions virtually impossible to defeat without wasting massive resources is unfun and unhealthy for the game.
And then there is tank Fizz... hey, let's take someone who many people (myself not included, I've never had a problem with Fizz personally) find a problem with as being obnoxious to play against, and then let's add an item build that makes said champion even more obnoxious to deal with.
Do you see where some people are coming from?
