I think its a game and there is going to be winners and losers. Sometimes you do good and lose, sometimes you do bad and win, sometimes you do good and win, sometimes you do bad and lose.
If you think of it from both sides, if you are stomping the enemy laner, the enemy team will think they are bad. If you are getting stomped, then your team will think your bad.
Problem is, what is good and bad? Theres more to it than just kills. Look at singed players. They literally do not care about dieing as they proxy farm along. They will eventually have towers be taken time after time after time, and what can the enemy do about it except chase him off like some fly buzzing around? Eventually you wont be able to kill him before he kills you, and so you need more and more people following him around just so you have minions to take towers with.
Its stuff like that, that i think of when people ask this question.