The problem with this game

You can put years into learning, watch LCS and streams and educational videos, learn the strengths and weakness of every single champion and become a master at the game.

But none of that matters when your adc leblanc throws a fit and afks 10 minutes into the game which at low level play (the majority of players) is bound to happen 50% of the time keeping you at a 50% win rate.

Of course this is an over-blown example but still holds some water about the game and what makes it truly frustrating.