lower elo's need to stop thinking they can play the skilled champs if they want to rank up

you wouldnt be silver or bronze if you could actually play vayne, kalista, lee sin ect. ive came across so many players on my smurfs trying to play the champs and every time i see 38% win rate lee sin 20 games 40% vayne then he has a 58% win rate with graves in 20 games hmm i wonder why?