Crimson Longinus
Legend
A total party kill is not the only failure outcome. Just one player character dying would be enough. The rules probably don't really "support" that well right now. But once the party needs at least something like a Raise Dead (or walk into a tavern to find a trustworthy enough fellow to fight on their side), it's a serious loss.
The rules don't support it well now and in a no attrition model they would support it even less. Because once the party has access to revivify or similar, in attritionless model casting it cannot have cost. So one character dying has no cost as they can be brought back without a cost.