I am browsing the old and new forums and I honestly don't get it. When somebody writes about him loosing because of team then most people immidiately blame him just because he lost some of games they found in his history. The same people however just loose the arguments when somebody actually gives a proof that it wasn't his fault. Then everybody is like "oh well just a bad game". That's it. People replying like this are players who never experienced such a streak of bad luck. I honestly do not believe, that those who replying have any recent experience in low elo and if they have then only as a smurfs.
If you have a decent player who happens to be in silver/gold and isn't on skill level of a challenger (he obviously wouldn't be where he is) then it's HIS fault that he is stuck because this is in fact singleplayer game right? There are no other four people on the team who can ruin it. It's all about that one player because he has somehow possesion of all teammate's keyboards and mouses right?
Players are being punished because their teammates feed, rage, go afk or just playbad even for the rank their in. You start ranked game and you have to go through SEVERAL stages where you have to be really luck not to lose before the game even starts.
You enter champion select and from then on you can lose in the very beginning. Somebody gets autofilled and decides to go troll. He takes your position and you can either start complaining (which results in him feeding even more) or adjust to that fact and pick his lane. Either way you lost this part of the game and your chances of defeat increased WITHOUT your involvement.
The other problem is that player might just pick a champion which is obviously not gonna work. Can you prevent him? To an extent. You can ban his champion which resuts in him trolling anyway. Or just can let him pick which results in him feeding later. Anyway you are getting small defeat again before the game actually starts.
There is no solution to this other than leaving which is loss again. Riot won't let you leave the trolls you just have to stay with them because otherwise you loose LP/promo.
If you are lucky in low elo game you get no afker, one feeder and two average players. This means that game is winnable simply by the fact that no directly sabotages the game. Enemy has similar composition except they either don't have anyone decent or just can't cooperate and bad composition.
If you have neither luck or unluck then you get just two feeders who are not doing it on purpose (or are they?) but this means that either some lanes or jungle is losing. If you have decent jungler you might actually hope for the win. If you don't? You lost the game because the feeding lanes will keep losing. Even if you are really ahead then you can't just leave your lane all the time. You can help one lane like every 2-3 minutes but they other lane will keep losing and more kills the enemies have, the worse your team plays because in their minds its already lost.
If you are unlucky then you get afker, two feeders and MAYBE just MAYBE one average player who will lose his lane too because enemy will cooperatively take him down.
No matter what you are always dependant on the match making system and you hope that you get at least balanced teams.