What's the deal with... "X champion is broken" whenever somebody gets fed.

Just had a Vayne trash talk me in all chat today, because I played Akali (who I happen to main.) She then continued to keep talking, about how broken she is, and Akali needs a nerf, and etc, etc, etc.

I honestly can't tell if people are joking half of the time, I literally went 14/4, and you fed me my first 2 kills, what the hell did you expect. You can't really complain about "X" champ being broken without 1. having the experience with the champion or 2. Having the game knowledge and statistics to know it's broken.

So please stop calling my champion broken, because I'm beating you with it.