I've come and gone from league multiple times for various reasons since the beginning of the game. The times I've returned to play I usually find myself stuck in bronze for a while(getting the hang of the game etc) before I can climb back up to Gold IV, which is about where I top out before I have to put league down because I gotta keep up with RL. So I'm not amazing, but I do understand how it is that you get out of Bronze and even Silver.
The first thing to realize is that once you play enough you average out to where you belong. You can blame your allies on a per game basis but given enough games the reason you're still in bronze is always you. The trick with Bronze players as you get closer and closer to silver is that they are not terrible players.
They are just really inconsistent with the basics, like last hitting, not claiming objectives, map awareness, understanding kill potential, etc which means if you're in Bronze and having trouble breaking into silver your basics are inconsistent.
For every game where you point a finger and say no one could carry the game there are probably are bunch of games where you're the guy to point at, when it finally is time for you to leave bronze you'll notice that you stomp out all your games against the players because you consistently take all the small advantages early and its ultimately reflected in those stupid 17-4-10, 22-1-6, so on and so forth games where you just straight up carry because you stop making the stupid mistakes endemic to bronze league and you snowball because the people on the other team are making those mistakes.
When you break all the bad habits of bronze players you straight up rock them 90% of the time and you'll carry. When you're firmly in silver you will stop rocking games like that and you'll have go through the same process of figuring what it is you're screwing up that's preventing you from carrying in Silver league, its the same stuff but even better, better map awareness and a greater understanding of the match-ups(kill potential, power spikes, ideal builds), and for every league there are things that if you don't understand the people who can carry at that level carry because they see things you don't about match-ups, objectives, warding, itemization that you don't understand.
There is a lot of nuance to the game and as the game progresses you accumulate power relative to the enemy team, most noticeable in your lane at first, and then, as the game progresses across the map. If you really understand league you can accumulate enough power to outright decide the game. You can't just win your lane, you have to win your lane and then use that power to hamper the progress of the largest threat to your victory on the enemy team. So its not even about who fed on your team its about you not feeding, and then using what advantage you gained to go shutdown whoever got fed on the opposing side which can be a lot harder than winning the lane but easier to do if your CS is on point, you get kills in laning phase, don't give up kills, and ward well(not just for yourself but for your allies). Little things add up in this game, understand what the snowball effect is and why it occurs in LoL and then play to create effect every time and every little thing you do in the game starts to matter more. Getting out of bronze is not hard but it does take focus it really isn't other players its you. The same reason some people think they can't get out of bronze is the exactly the reason why in actuality its not that hard.
It helps to pick strong champs, it helps to que with people you trust to maintain a certain standard of focus and game play, and even if you don't pick meta champs, it helps to play the same rotation of champions over and over so you get really good with few champs than playing champs who are so different you never get to excel at specific role or play style. It helps to practice controlling champions, practice last hitting and aiming abilities, know the mechanics. Its a lot of things but "git gud" is the best way to put it, because you can take it as a campy insult or you can take it literally as a suggestion to improve your game play by practice, study, and conscious intent. You will lose some games, but you can train yourself to carry most games at bronze level if you put in the extra effort