Riot, this was the most miserable game of my life

I've been going through an enormous climb lately. With recent solo queue success, within a few days I made it from Silver 1 to Gold 3 without any losses (until this morning). As expected, this threw my MMR way up. After getting lucky with so many good teams, the system thinks that I'm way better than I actually am.

I'm being consistently matched with diamond and plat players that I really can't play against. It's miserable.

But the next thing kind of just defied what I understood about normals.

I went into a teambuilder lobby, and got matched with 3 diamond players on my team. I was supporting with several new champions lately, because I want to refine them before I start playing him in ranked. Now keep in mind, I thought that MMR for normals and ranked were independent of one another.

So I check up, and I don't understand why I'm playing with these guys, they're way ahead of where I am, right? My adc, he's throwing so much at me and I feel like garbage. I'm under so much pressure and there's so much around me going on that I'm not used to in the lane, like him pinging things that I didn't know what they meant, and just stuff just threw me for a curveball. I was getting yelled at, cursed at, and honestly, I don't blame them. I could tell I was the weak link of the team, I was playing way worse than everyone else around me. It's like matching gold players with bronzes, and trying to get the bronze to understand and comprehend everything on a gold level, it just doesn't work.

I don't want this to ever happen again, but I really want to know why it did. Any insight would be much appreciated.