what is up with the mmr system

I'm kind of annoyed by the fact that in the past 10 games the mmr system placed me on teams with a skill level much lower than the team I go up against... I'm tired of going 20-35 minutes into the game with 3-4 deaths max then towards the end game I get 4-8 deaths just trying to not lose the game making my overall score look bad because 1 or 2 players on my team fed 5-10 kills in the first 20-30 minutes of the game... Does the mmr system even recognize getting screwed by other players? and why does bronze have a mixture of people who just absolutely suck and then people who should be in gold? there is 7 tiers why arn't the skill levels spread out between them if I go every game with less than 4 deaths (if my team doesn't feed) why can't your system actually pair me up with people on my team who do the same? I honestly don't feel like sitting a whole damn game behind a turrent either because my team died till the game ends either P.S. also annoyed going up against teams built on movement speed (can't catch or run away from) or the fact that in bronze no one picks champions based on the composition of the other team (atleast on my end)