This concept gets tossed out a lot by people down-voting threads complaining about a specific champ. It's also entirely true. Take for example Zilean, who I was recently explaining to somebody new to the game:
He has a 600-1100 base value heal which scales off of 200% AP, an AoE stun with attached damage, a 99% slow which can instead be used to speed boost allies, and can top up his allies XP to help them out-level opponents.
Sounds pretty broken, doesn't it? The heal is his ult, which requires his target to die and then makes them sit there for a few seconds. The stun is his Q which requires him to land two skilshots on the same target, the slow is his E which really doesn't have many strings attached other than CD and mana cost, and the XP bit is his passive, which is on a really long CD.
This got me thinking about other champs..
Anyone who wants to, name a champ, and I'll make them sound OP (probably not to the degree that is possible with someone like Lee Sin, but still).
And, on that note, as I know they'll be mentioned by someone:
Has a AoE ability that applies a physical DoT and armor shred (which boosts the damage of the DoT), has a ranged point and click damage source that refunds mana if it kills something and can slow people, has a suppress which also displaces the target, and his AA's reduce the target's damage output and can slow them.
The armor shred DoT is his E, which is a skilshot, the point-and-click damage is his Q when he targets someone affected by his E, the slow on that and his AA's is a passive while his W is up, and the suppress is his ult, which is channeled and displaces both his target and him.
Has a ranged AoE slow which follows you around and seeks out targets, an AA augment which then follows you around and seeks new targets, a source of sustain which can follow you around, can reanimate allies, scales better into very late game than most hyper-carries, and all his abilities grand him bonus AD and damage reduction.
AoE slow is his W, AA augment is his Q, sustain is his E, and all of them summon minions with decaying health, reanimate is his ult (which only reanimates for 10 seconds), and the bonus damage and DR is his passive which gives him bonuses for all active summons in game. The scaling bit isn't made up, but isn't really tied to any abilities, it's fully possible for a built Yorick to solo entire teams _and_ Baron late game (real late game, not 40 minutes).
EDIT: Apparently some people are failing to get that I'm making fun of all the people who do this regularly as their argument for nerfing a champion.