Riot's matchmaking makes so much sense

I started a 3's team just for shits and giggles. We won 5 in a row and placed into Silver 2. Won two more with an average of ~34 points a game. My next match? A Master team that literally had never lost a game, 51-0.

So why, may I ask, am I supposed to prove that I'm a Master/Challenger level 3s player in order to get out of Silver? Please explain.

Please. Explain.