That's so interesting! I think the fact that they nail the tech so well makes it intuitively surprising that it didn't come first. Not pixar but similarly, when I saw the siggraph talk where Disney Animation showed off how they do snow rendering in Frozen I wondered whether the tech came first
That's also a case where the tech came a while after the story. Our early snow tests on Frozen looked pretty terrible until the MPM simulator [1] came online later.
Did the MPM simulator get used in practice for Frozen? I talked to a few sim TDs (or whatever the equivalent Disney title is) and they said it was too slow at the start for practical use!
