i think one of the problems is the balance team and a percent of the player base wanting X champion to be buffed. its kinda like inflation but with damages.
So i main Rengar for instance. he is one of the worst assassins in the game i dont even play him as one anymore because litterally every other assassin does his job better.
Despite this, I do not and will not ever say rengar needs to be buffed. the others need to be nerfed. Rengar is a good champion with decent stats. but compared to Zed, Talon, Fizz, all other assassins. his damage does not only fail to compare. But his kits also fails to compare as well.
Zed gets to escape with either ult or W. two abilities that are meant for engaging.
Talon has his R to go in and E to escape any scenario.
Khazix has 3 invis and jump resets.
Fizz has is E and Q.
Rengar however. he only has his ult to engage and once he jumps in He HAS NO WAY OUT WHAT-SO-EVER. aside from flash and whatnot everyone else is immediatly better then him in damage(zed and talon and fizz can wipe 3/5 a team or oneshot a single target) aswell is tons more mobility.
Despite that. Rengar does not in anyway need/deserve a buff. the other assassins need to be nerfed.
and this applies to all classes and all roles. Instead riot just buffs. oh vayne is strong? buff all counters. oh all of vaynes counters beat her now. buff vayne. there is no reasonable logic in this