Yeah, that definitely seems to be the biggest issue. I'm low silver struggling as I keep getting teamed with many Bronze players.
I described Bronze to my friends like something from a horror movie. It's like floating in a lake when suddenly hands begin to emerge from it and try to pull you down while you struggle to stay afloat.
The annoying thing is, many of them are really good mechanically (way better than me), but if they just read the map little different and communicated a little more honestly, they wouldn't be there.
One of the game last night, playing as a supp, we faced a Graves and blitz who simply won the lanes against us. That graves was simply too good. Got over 200 SC in 20 min or so and got couple of kills of our jungler as well.
Him and Blitz didn't even attempt to take our turret and was still standing until we won the game.
Really baffling!