Why does Riot keep giving me Iron players and players that bronze 3 with 1200 games in my promos???

I had a good winrate with Shen then when I get close to promos its impossible, players with 1200 games in bronze and not a decent winrate and an iron adc meanwhile enemy team gets two silver botlane HOW DO I CARRY THAT???????? Look at my history. I do well meanwhile my teammates (not all just the, iron player and the one with 1200 games) feed the whole game. THEN THE ENEMY TEAM HAS A DECENT TEAM IS THIS FAIR???????? WHY DOES RIOT GIVE SHIT TEAMMATES?????????