Any difference between Silver and low Plat?? Not really

I know what you're thinking, "Uhhhh there is a huge difference between garbage silver players and plat players are you retarded???". Listen guys, just my personal experience I have done better than any Plat 5 or high Gold players I have played with and against, ever, end of story. I am currently S5 but done with ranked for this season. I just played a ranked flex with a Plat 5 on my team who was Plat, Gold, Gold, Plat, from season 4 till now respectively. Everyone in the game was bronze and silver so it should be gg ez right? Our Plat 5 adc had TRIPLE the other adc's farm throwing up 150 cs in 14 or 15 minutes. GG EZ RIGHT???? Hell no. For what ever reason this player was not able to get a single kill until she was already 0/4/2 but still having the most gold in the game by quite a bit. How does this happen? Honestly I have no clue how you can be a Plat adc (main? it looked like it on match history) and not know how to position and get kills to help carry your team to victory. I wanted to say she was boosted hard, but every season?? Thats a lot of money lmaooo. So i have no clue. And this isn't the first time either. Another flex with a Plat 4 Syndra mid who was plat the season before as well started off 0/9/?. I just don't get how this happens honestly. Just kinda ranting over here but with good reason (I think so anyways). Obviously higher ranked players are, or should be, better than anyone ranked below them.