This post is purely about Solo players. Duo's bring a new problem altogether, that I won't discuss here.
Here it is:
There are two different ways of playing this game for Solo players. And only one of these two ways, will allow you to climb up Riot's MMR system.
1) You focus on your opponent in lane. You expect everyone to do their jobs. Even if your team loses lane, at the very least, please don't feed.
You get high CS, you win your lane, and you have map awareness for your general area. You help the Jungler when he's near your lane if he needs help, but you mostly dominate your lane. You win CS, you win the KDA battle, you take down their tower, you don't give the enemy Jungler any Gold.
2) You play the Global game. You exert your influence on the entire map as much as possible. You take Teleport or some other high mobility champion. You leave your lane at opportune times and help gank. You annoy the enemy jungler when possible. You win your lane and try to "lead" your team by telling them what objectives to do, etc...
Now, only the #2 method of playstyle will allow you to climb Riot's MMR system.
However, if you look at this game logically, intuitively.... like any other game on the planet.... you should be able to expect your team to be somewhat competent at their jobs. So, you focus on YOUR job.... you do well, but you lose the game. You are stuck in "ELO HELL" (old term) and cannot rise in ranks.
Then, you go to the forums to complain, and people just tell you to get better. But you scratch your head and get frustrated. You win your lane 99% of the time in your matches. You get more kills, more CS, take down tower... you are stronger than your lane opponent and sometimes can even take on 2 enemies at once and win or damage them both very badly. And here people are telling you to get better?
This is why.
This game doesn't let you play logically.
You have to learn the "Global" game style in order to rise (for Solo's).
And honestly... it's not fun. Having to shoulder the burden and add a lot of stress on your shoulders is not fun. Logically, one should be able to focus on their job, do really well, and influence the game enough to still have a chance to win. But that's not how this works at all.
I don't know what the solution to this is. But LoL really only promotes -1- style of play, the global style. Playing anything else gets you frustrated.
Maybe RIOT has balancing issues with the game, I don't know.