70% win rate to think about climbing ranked ladder?

Not exact math, but it looks like you need over a 70% win rate to climb ranked ladder.

I dunno, this season its bad enough for a noob player like me. A bunch of silver players get knocked down to bronze with 7 / 10 in provisionaries. Which I also had and went from bronze 2 to bronze 5. Which I was stuck in for weeks between trolls, AFK's and silver players (whom had a hard climb, but did make it).

But then I get a low 9LP for my more than 50% win rate (before my last 4 horrid games) And when I loose, I take a 25-30LP hit. 1 loss erased 3 of my wins, And some of those losses I was 11/5/20 or such, I almost carried the team in a few of those games. It just seems so unfair. Seriously I could not climb this ladder without winning 7/10 games.

ELO maybe a myth, but this climb seems impossible even without AFK's and players more noob than I who just joined bronze on my team all day every day.