If you have a 50% chance of winning or losing, then how does your skill matter? A good player should win more then half of their games, and unskilled players should be losing more then half of this games. What you said is actually true, Riot creates the illusion of a fair game (where everyone wins and loses the same) by making good players lose games to keep them in line and giving bad players easier match ups to help keep them from never winning and A) Losing Interest or god forbid B) Actually getting better.
When actually that is not fair, I should not get a team of 3 golds and a plat if I'm bronze 5, I don't deserve those allies, and I could afk and my team would still destroy the enemy. Being Bronze 5, I'm also not garbage, having been playing this game since s3. I know how to play. I know what I'm doing. If I mess up I made a mistake there is no "oops I'm new to this"
But I can LOSE a game where I'm 10/0/8 , no deaths, fair amount of enemy take downs, assisting in team fights, I roam top and bot and help get them ahead, and still lose. Because my other 4 team mates all had AT LEAST ten or more deaths, never grouped, picked off solo split pushing, support trying to take a gromp in enemy jungle, ect. Why? Why did Riot match me up with these other 4 people? Because in their Algorhythm it was just time for me to lose a few games to make up for my winning streak to preserve the illusion of the lose 50% win 50% of your games fairness.
Fairness should be you winning as many games as you are good. You should be paired with team mates that have comparable skill to you, a player should EVER be put on a team filled with people BETTER then them or WORSE than them. But hey whatever.