"Here, have some feeders, absolute idiots, some people with a <30% winrate, and one tricks who were autofilled, while the enemy team is made up of premades and people on win streaks!"
... remind me why the fuck we have promos in the first place. 80% a coin toss, 19% team comp, 1% individual skill. What does that prove, exactly?
And then try to tell me that the system doesn't try its hardest to keep you at 50%. I'd love for you to prove that it's just a coincidence.