Why do losing streaks happen?

Seriously, does matchmaker intentionally place you with the worst teammates possible so you can lose? First I had a game where Swain top fed Kennen hardcore, teammates getting constantly caught out due to never warding their lanes so akali got fed, next I had a 3v5 game bot lane decided to just afk for most of the game, after that a game with a troll lux that despite being last pick took mid and refused to communicate with team all game and forcing someone else who had never jungled in their life to jungle and me mordekaiser to top against miss fortune (got raped), after that I had a game where I went adc as jinx and had a zilean support who continually fed lucian by walking into the exact same bush over and over again that had a volibear support sitting inside, while that was happening yasuo fed Ryze hardcore and enemy jungler went legendary, and then I started feeding because we got raped every teamfight.

All of this caused me to drop out of silver IV in one day, so why do losing streaks happen is there anything you can do stop the feeders, trolls, and afks?