Karthus is unhealthy for the game...

So I recently had a game as kindred and I was playing against karthus jg with dark harvest. I was able to shut down karthus and steal both of his buffs early. I even managed to steal his krugs, gromp, and raptors, leaving him with only his wolves. I killed him 3 times during all of this and my riven even killed him twice, making him 0/5 at around 7 mins in. Karthus never ganked any lanes, and rarely even showed on the map. All he did was use his ultimate to secure kills top mid and bot, and there was nothing I could do about it considering I had no vision of him. Come late game, his ultimate would do half of my hp and his q doing 1/4 of my hp, and all this for farming and pressing r?This in my opinion is terrible game design and is completely unfun for anyone to play against. Does anyone know if karthus is receiving a nerf anytime soon, because this is just not ok for the game.

EDIT: keep in mind karthus ended up doing a total of 70k damage by the end of the game. O_O