Why people say Juggernauts are OP

The point of the Juggernaut reworks was to make Darius, Garen, Mordekaiser, and Skarner big tanky walls able take nearly as much damage as a full tank while still being able to dish out considerable damage. As a cost, they wanted to make these guys slower than Cho'gath with no boots (except for maybe Garen, who's still kinda fast). The bottom line is that Riot wanted people NOT TO MESS WITH JUGGERNAUTS! These nerds have almost no mobility. So just DON'T MESS WITH THEM. Don't charge directly at them, Don't 1v1, Don't eat their sandwich. Multiple people work well in taking them down (Although, who doesn't it work well on). But I cannot stress this enough. DO NOT MESS WITH JUGGERNAUTS

So when people say they're OP, they mean "I messed with a juggernaut, the exact opposite of what you're supposed to do against one, and died. Therefore, juggernauts are OP"