So I just got demoted from silver 2 to silver 3 but was it realy my fault? Do I realy not belong?

I don't feel like the enemy is better than me to be demoted, in fact, wtf does it even mean to get demoted? the game doesn't take many many factors in consideration when you win or lose, things like afk's, trolls, people trying something out for the first time and get shit on, etc etc etc.

Why did I lose the game which got me demoted? that might have something to do with the enemy having a possible smurf kayn who went 25/5 or the team riven who went 5/14 and did the least damage OF THE GAME even less than our blitzcrang support, or our jungle twitch wich got shut down early by the enemy kayn (possible smurf) and ended going 3/10.

I'm not saying I played well but I did played decently and kept my cool and did the most damage on my team by far and got a neutral score of 7/8 which if you compare it to my teammates wich all got double digit deaths except blitz and me. I also got 2 or 3 towers and didn't lose my lane.

So in conclusion, this game demotes me for not being good enough to carry my scrub team? In the message it says "you have been demoted'' like its 100% your fault. In a team game where everyone matters to win and were 1 player can make 4 others lose so easly why does only 1 very narrow view of your skill is taken in consideration to calculate your skill/LP loss etc.