Blades in the dark "stress" rule and Willpower Points

Heya !

In a "Get in the trunk" campaign, the Handler got inspired by Blades in the Dark and allowed the players to spend willpower points to boost a roll (I think it's +10% by point spent) or add narration details (for instance, not related to the campaign to avoid spoilers, it could be "Need a smartphone ? hmm yeah, ok, a guy across you in the bus is apparently scrolling on his smartphone, but that'll be 2 willpower points."

Has anyone tried that at a table ? My first thought was that it adds a new way to cut down willpower points besides sleep depravation / fatigue, but not sure if it breaks the game or tone down the gritty spirit / stakes behind a roll.