Why the game is putting us with low level players against +150 level ?

In my last game ( as many others ) i was the only one above level 150 all my allies was under 50 ( 37, 25, etc ) . I know level doesnt mean anything but low level player are new in this game or are just smurf ( very rare ). Even if they manage to climb in diamond elo games, they still don't have the exp to know their limits, champions, patterns ...

Ex : Recognizing when you can finish or not. It come with game xp no matter how good you are.