It's always the can't beat it, than nerf it mentality. Try playing a character that you have trouble playing against and see how 'OP' they are. The possibility that you can't reproduce the same kills with said character should mean enough
I've always had trouble with Pudge (hate his looks, hate his hook and hate his 'fresh meat!!') because some of them are so damn clever hiding in the tree's or off sight just to grapple you and kill you. Yet, there are always those pudges in either opposite or same team who grapple their own team members away when they can last kill someone or grapple creeps instead. That happened so often to me when I wanted to kill someone and this damn pudge grapples me back which allows them to escape >.>
In any case, hero's are ment to be stronger than some others because they all have different counters. You're not supposed to kill every hero 1 on 1. But the thing I like most is that ANY hero involves skill and that gives you a bigger chance of killing someone who is supposed to be your counter.