I legitimately can't win games with a duo, why?

My friend isn't the greatest player, I know this already, but he's carry-able at least. But for some reason every single game I play with this friend I get not just him feeding, but literally everyone else on the team too.

I've been told this is some kind of "punishment" for duo queuing. That the game kinda stacks the other team to make up for us being a duo.

I realize it's not my teammates' fault that they can't keep up with the other side, since they're all silvers and the enemies are not.

My question is this; if it's punishment for duo queuing, how is that fair to the other people on my team? And secondly why include the feature if it's just going to destroy my MMR and 3 (4 if you count the friends') others' at the same time?