Why is this game designed to keep you in low elo no matter what?

So this is my first year played ranked somewhat hard. I always focus on what I can do better and what I can do to help the team win. If we don't win I blame myself and try to find ways to what I could have done to win. However the last week or so has shown me that this game no matter how well you play is designed to keep you in low elo. I've climbed from B3 to S4. Going from a 41% win rate to 49% continuously. But i've noticed lately that something doesnt seem right, I went on a huge win streak about a week and a half ago where I had something like 17 wins and 4 loses, and you know what? My LP I gained went down significantly, for whatever reason(was gaining about 25 lp per win, and went down to 19 a win, 20 a loss) its now evened out around 20LP a wn and 19 a loss) but what was the reason for this? Also I've noticed that people who have horrid win rates(25-40%) are a higher division then me or the same....that doesnt make any sense...if there winning less games, shouldn't they be falling down divisions? It almost seems like Riot designed it so that bad players get to stay in divisions like Silver even if they don't belong there. I take my point into question with this person who I found in the same division as me.

https://na.op.gg/summoner/champions/userName=dravendrake

Now, he has no prior season rank, he played only 14 games, and went 2-12, which means at best in his placements he would have went 2-8. For someone who had no prior history of a rank in any seasons, this doesn't make any sense to put this person at Silver 4. They average a KDA of .91 on there champs and has a win rate of 14% but yet was allowed to be placed in Silver 4, does that not seem completely messed up?

Why was it that I was placed in Silver last year, went 4-6 in my placements and was put into Bronze 3 and have to climb out of bronze, and yet this guy gets to go straight to Silver 4, yet he lost 86% of his games and fed most of the time? How is that fair and why is this designed this way??

Here's a link to my profile as well

https://na.op.gg/summoner/userName=mithstrifer

Ignore the ADC games as I figured I would try it out, I mostly play Jungle and a little support.