His Q only does considerable damage on return, which is easy to dodge if you're not braindead.
His ult can be dodged by blinks or even very fast dashes, not only late game it does so little damage it becomes a kiting ability more than anything.
Unlike other adcs (except jhin) graves also has to count his shots, kite between reloads and use E for quick 3 shot burst.
Any tank worth his salt will just block his shots because his shots dont go through units, and in lane fighting inside a minion wave = graves without AA.
Also every adc and mage out ranges him and without hitting his basic attacks, his E isnt up nearly as much as it seems.
Case in point, learn to play around him, if you let him get in your face stack his passive and and reset his E you'll get dumpstered, just like how vayne can stun you into a wall and shit on you.