Unexperienced Player Ranked

So,I just had a nice game.It was good.......except for one player.A Vayne that went 4/16/5.No I don't blame her for feeding.I neither blame her for being bad.The only thing I'd blame her for is being unexperienced.However who is to blame is the system and Riot.And yes,the game was just a free win for the enemy team because of her.She was dead like half of the time. It's just purely stupid that the required EXP amount for players to reach level 30 got decresed.If someone gets level 30 and all of a sudden he decides to start ranked (after having bought enough champions) and propably ruins games for the rest of the teammates. Right now the starting MMR shouldn't be that of a Silver player.With the amount of games required to get to level 30 Bronze 2 would be way better or maybe even Bronze 1.