Why is normal matchmaking terrible?

Usually play ranked, decided to play normal, (I'm silver IV btw) and my entire team was silver. Cool. Four other players the were silver, fine. Then there was a plat V with over one thousand normal wins. Don't give me that normal mmr vs ranked mmr thing. You're telling me, this plat V with over one thousand normal wins has the same normal mmr as all these silver players and still dominated the game? Are you kidding me? If he/she were bad, but still in plat V casue of duo q or something fine, but this player was just dominating in lane and in game. How is that fun? Yes he was premade with a silver, but he had a better ranked than I do (silver II) and onlt 30 less wins. Could league really not find ANYONE ELSE? And it's like this, EVERY SINGLE NORMAL GAME. I'm going back to ranked. See stats here: http://www.lolnexus.com/NA/search?name=raging+inferno&region=NA Edit: Forgot to mention, the one thousand wins was significant because no one on my team was at that, one was as low as 269 wins (who was terrible btw).