"I still don't get it"

A simple explanation.
Blind Boxes draws its inspiration from capsule toys and gashapon.
Replace the toys with NFTs
Think: PopMart for NFTs
PopMart is the wildly popular collectible figurine platform that is using a gamified selling model. With PopMart, artists designed figurines are sold in boxes that do not reveal what item is inside. Instead, collectors are presented with a chance to get a range of collectibles of varying degrees of rarity and value. Since items of exceptionally high value are dispersed in their inventory, collectors are incentivized to purchase boxes until they get the item they desire.