Normals Matchmaking

What's up with riots shit matchmaking? I'm plat 1 currently getting placed with anyone as low as silver to anyone as high as Master. It's very hard to play a game where I'm against a master player and they shit all over 3/5 of my team and I end up not being able to do anything because 5 minutes in that player already has 5+ kills. It's hard to practice this way even though it's norms. I just wish it could be people who are around 1 below or above your division but not 3 divisions above or below (this does happen sometimes). So why does riot insist on bad players getting shit on and calling it "practice"?