Looking at a players hand is useful, as it lets you know if the coast is clear in the event that you want to play a powerful but vulnerable card
If they are featured as MTG cards, there are plenty of cards that match the Chaos Emeralds abilities
Eye of Ojer Taq is cool on the surface, right
If you're creating a Cube, you could proxy the entire thing, or just individual cards that are hard to get a hold of
A big driver of rising prices in previous Commander products are the exclusivity of certain cards (past examples include Flusterstorm, Scavenging Ooze, True-Name Nemesis, the free spell cycle from the Ikoria decks and more), so thats eliminated from these decks
You ship them your cards, they sort everything, grade conditions, find the best buylist prices across multiple vendors, and send you a check