Admittedly, this would require almost 400 mana to deck out all your opponents, but still, think of the possibilities
For those who aren't interested in milling their opponents, when used to mill yourself, high-toughness creatures in a Phenax deck can easily enable self-mill win conditions like Laboratory Maniac and Thassa's Oracle.
10 Chandra, Fire Of Kaladesh The Emblem Is The Goal Chandra, Fire of Kaladesh is a low mana value commander that is all about low mana value red spells
It provides another angle of attack and a strong win condition in an archetype that can often spin its wheels to no effect
If you want to pay 7 life to activate Griselbrand, but your life total is 6, you don't have enough life to pay the cost
In this scenario the card has what I have defined as low sentiment and seems like a great investment