its not just misfortune, not to be confused with miss fortune who also has more to offer than just damage and selfish protection, but the fact of the matter is that even leblanc has more to offer since she has better cooldowns on a larger portion of her burst and isn't nearly entirely skillshot reliant, you can't block most of her stuff and the majority of her damage isn't realistically dodgable. Ez can one shot people who have no business fighting high burst champs alone, good for him. But he does nothing else, personal experiences or not. When the enemy is competent AP ez becomes a huge burden. He can't keep his damage up giving them huge gaping windows during which they can attack all they like. Once his ult is down he's just another normal damage source, Hurray he does like 25% more damage if he actually lands everything on just the right person which wont happen against competent teams even if the player doesn't suck, actually its more likely to happen if he sucks and just sacrifices himself to almost instagib someone whos being protected because their team knows that's all AP ez can really do.
Worst of all though is having to play around having one of those on your team. Even when youre winning it feels really shitty because the midlaner can't do much. Its like playing with asthma guy just because he can shoot from the 3 point line but that's all he can do.