TFT Ranked Distribution
According to this, the TFT ranked distribution seems to be skewed toward the bottom ranks. Compare it to League of Legends, and you will see the difference.
The LoL graphs seems to follow a normal distribution more closely. I mean, the bottom 50% are in the bottom ranks, and the top 50% are in the top ranks. The very bottom rank has 1.5% of the distribution, and the 1.5% of the top are in the very top positions (starting at diamond 3). Whereas, the very bottom rank in TFT has 22% of the distribution
The lp gains are inflated, so it is fairly easy to reach gold, so I think people are just quitting TFT at iron, bronze, and silver.