Let's say you cast a Glorious End during your opponent's last turn, if you can untap, play a Gideon of the Trials and make an emblem, you won't lose the game to Glorious End, which means you just Time Walked your opponent for three mana in Standard
From a financial perspective it is a useful exercise to try to forecast which cards might be included in this set so that you can decide what you might need to do about it
They predate rarity symbols, which is part of why identifying early cards can be tricky without some background knowledge
Stonjourner in particular loves it because that adds to its Exoskeleton, meaning it prevents 50 damage from each attack
It provides immediate value thats easily compounded by cards like Doubling Season and Pir, Imaginative Rascal
Dave realized that each booster pack having a guaranteed, prescribed thing was very powerful