Are juggernauts too powerful?

ever since i started playing league, i have just had a thing for playing garen. he was cool and i liked his abilities and especially his ult. i got all the way to silver 3 with him and this was back when people did not want me to use him in ranked because they would always say that he was "underpowered". Then, the juggernaut updates come and the start of the juggernaut meta arrives. of course i like it because of the garen update but now, people say that juggernauts are all overpowered and i just might have to agree. garen and all the other juggernauts were fine before the update i think. they are extremely tanky and deal damage at the same time. they shouldn't be able to charge into your entire team and come out with a quadra or penta kill because the can tank the entire teams damage and still be able to have enough damage to kill them. tanks are suppose to be extremely hard to kill and have no damage. assassins are suppose to be easy to kill but deal tons of damage. juggernauts just take the purpose of all of those away and put them into an unstoppable killing machine. one game as darius, by full build and level 18, i had 330 ad, 4257 hp, and about 150 armor and magic resist. i dont think that it should be like that. i just wanna know your guys's opinion on that. thanks.