QUICK ASIDE: I will comment below on one of my former diamond accounts: dadnekton. I don't recall the name of my other one.
The reason I can't get out of bronze is because Riot has done too much to minimize the influence of skill. The impact of skill on the outcome of a game (win/loss) is diminished by a game change when the game change causes elements other than skill to have more influence on game outcome. For example, if randomness matters more after a game change, it follows that skill has to matter less. Riot has basically equalized the playing field in terms of skill with these implementations: an extremely punishing bounty system - punishing good players; a severely punishing amount of kill xp on targets that out level their killers - punishing good players; death timers that scale with level - punishing good players; a lot of blatantly overpowered champions which diminish the influence of skill, because said champions are too strong to fail even in the hands of bad players - punishing good players; catch up experience for junglers that allows them to sit on a good players lane all day whilst keeping level parody with everyone in the game - punishing good players; randomness in terms of which elemental dragons spawn, which diminishes the influence of skill, because the influence of randomness has increased.
This confluence of game changes from Season 6 onward has basically culminated in League of Legends socialism, because players with the skill that should afford them the ability to climb to higher ranks has been crippled, bringing them down to an even playing field with the bad players. If you align with socialism politically that's fine; it doesn't work in League of Legends. If I wanted to get out of bronze I could I suppose, but because skill matters much less, it will take me many more games than it should. I don't have time to waste on a video game where bad players are rewarded while good players are punished to the point where skill expression is nigh impossible. Good riddance to you, Riot.
EDIT: If you're going to look through my match history and say "you went 3 and 3!" I literally have 2 just okay scores in ranked so far, and it is hard to maintain a good score when your team is feeding. I believe I have 2 okay scores in ranked, and 5 very good scores.