Why do people hate Heimerdinger?

Well, people often threaten to report me just because I pick him, for starters. In game, the other team always tells me how easy he is and how bad I am, even if I win the lane and kill them a lot. What makes him such a bad champion? I started playing him when i first started playing LoL and have won a lot of games with him. I never troll, so why do they want to report me? Heck, I've even seen a Heimerdinger jungle before ;-;. I'm still relatively new to the game, so please help me understand in simple terms ;-;.