"High Skill Caps"
You know how when he sets up that one little line on the ground, and immediately shoots his Q at you, and manages to chunk half of your health before jumping in with his other five abilities to finish you off? You can't deny that if you don't have 700 armour, he'll be able to instakill you before 20 minutes with very much ease.
Just... His base damage is massive, and his AD scaling is also massive. He's simply not fun to play against, because his simply does way too much damage against most champs.