Nerfs based on Counterplay, not overall strength work for competitive but not lower tier play
So people still don't get this. They ask, why are silences removed from so many champs. This is because silences are (were) put mostly on burst mages/assassins with targeted abilities (Leblanc, Viktor, Kassadin, Talon). As Riot has stated, short duration silences felt more like unresponsiveness than actual cc, and silences need to either be on spells with counterplay or on melees.
I'm not targeting this post at these champs, or even at silences overall because that's only a small example. The main point is, unranked, inexperienced, or even bronze/low silver players struggle against champs like Yi. Do you see Yi in LCS, or even in Gold/Plat (yes yi mains play him but thats it)? Do you see Riot nerfing Yi, despite the fact that he pubstomps and is frequently banned/picked at lower ELO? No. Because Yi has a clear weakness (hard cc) and that means he has COUNTERPLAY. Compare that to (pre-nerf) Kassadin. With all targeted/aoe spells AND a silence, he is low counterplay. Low counterplay champs are INCREDIBLY hard to balance, they are often either op or worthless. Often they are reworked/changed to actually have counterplay, such as having a targeted spell made a skillshot.
So yeah, before you complain about balance, consider whether you are just failing to acknowledge the champ's counterplay, or whether they are actually overpowered. This doesn't mean champs with counterplay can't be op, or shouldn't be nerfed, it just means that they are less likely to be nerfed (for good reason).