Nothing sucks more than losing to Yi, Riven, Yasuo, etc when you perfectly counter them mechanically
But a Yuumi is attached, making your counter completely pointless because muh heals, slows, auto giant stun of lolz. while untargetable.
Who the hell thought an uncleansable super buff with infinite duration (yuumi) was sensible? They tried this with other heroes in other games and always massively lowered the actual ability of the attached hero to make it somewhat balanced.
Yuumi can never be balanced because there is no way to target her to stop her buffs period. You gotta kill a super hasted, healed, buffed from item passives, aoe stunning, aoe slowing, roflcoaster on a hard carry.
When Janna is good, you kill janna to stop her from being good. How do you stop a Yuumi? Win before 10 minutes