Matchmaking Problems With Low Levels

So today I learned that one of my good friends plays league of legends. (Hoozah! we can play and have fun and screw around in normals) He is a level 27 Vi main who is okay but is new to the Moba experience and hasn't 100 percent grasped the concept of things like objective control, itemization etc.

However this is not what this post is about. This post is about how messed up the matchmaking system is when playing with lower leveled players.

So I invite my 4 friends to hop on and play some league. The 4 of us were all level 30's ranging from gold-plat Elo, the only non level 30 in our group was my Vi friend. Naturally we booted up a game where I played Riven top against a Nasus. Level 1 went pretty standard simple farming and what not but I noticed the enemy Nasus was acting strange. In 2 waves he accumulated 3 farm, yes 3 farm and he didn't even have 1 Q stack yet. I hit 2 before he did and instantly engaged I got firstblood and felt pretty good until he came back to lane with a Amplifying tome. Thinking that maybe he was trying to rush Sheen or something I carried on with the game. My friend who was mid was playing Ahri vs TF and had 6 kills pre level 6. I thought maybe the laner was lagging or something but then Nasus came back to lane and I killed him immediately. This happened 4 more times before level 6 and at this point i decided to Lolnexus our match. And oh my lord. The enemy TF was level 12, his first game in normals ever. Nasus was level 7 and in all of his games he had about 12+ deaths. Looking at each of his matches I saw insane statistics. A yasuo in one of his games had 46 kills and 1 death and was level 30 plat 2 vs a bunch of players below level 20.

This utterly shocked me. The lowest level on our team was my Vi friend who was level 27 at the time, and for some reason the game matchmade us with kids who hadn't even hit level 20 yet. We continued our game and at 35 minutes my Nasus had accumulated 20 farm, and 1 Q stack and was still trying to complete his Trinity force with 13 deaths. The TF was around the same and Nasus typed in all chat "I wish this would end already, this happens almost every game." so I told him he could surrender by typing /ff so he did and when his team quit and the nexus exploded he said "Wow thank! now i dont have to play 40 minute games and get killed 20 times!"

WTF????? This kid didn't even know how to surrender and i was playing against him. Once again, the lowest level on our team was a level 27! And we faced level 7's! Why is this happening? After the game i added the Nasus and TF who were playing with their level 25 Yi friend and they all told me the same thing. Every game they face level 30's who are far superior players and just get dominated. Out of all the games that were listen on their match history they had only won 2!

TL;DR why does the matchmaking system create such unbalanced teams when playing with lower level players?