Especially one who would royally abuse it due to the fact that she poor and hungry. And quite greedy.
To be fair, I doubt anybody wouldn't use that as a threat if they were the ones holding the world together and they were STILL stuck in a dead-end shrine without food.
The best part is how stoically deadpan she is throughout the whole thing. From betraying her best friend to cracking the goddamn sky, no hesitation or remorse whatsoever.
Reimu's yearly reminder to Yukari that, regardless of how insanely powerful and intelligent she is, her entire plan still banks on the cooperation of a lazy miko.