"If everyone was amazing at the game, bronze would be full challenger players."
Naw, bro. You got it all wrong. The thing about the League system is that it's not a ranking system, rather a placement system. I'm not going to log onto League of Legends to be given a message that I'm the X'th best player in the region. Rather, when I log onto League of Legends, I'm given a tier and its division that is relevant to its matchmaking ratio. So in wording, the concept of "ranked," is more of your rank; your grade. In fact, the only tier that is actually RANKED is Master-Challenger.
Take it like an advanced classroom (Diamond) full of 4.20 GPA students that probably stole your spot at the state's top university. They're all very good at what they do, and everyone gets above a 90. Some are a tad worse, but the scores are relatively the same. Now, if everyone was like that, the normal education classrooms (Olympic Elo) would not be filled. In other words, there would be no shitters to fill bronze, silver, gold, or platinum. Everyone would be in diamond and above because they're simply at that skill range.
sorry for this shitpost i was bored and wanted to just type away